The Best Flank Steak Marinade with Green Onion Garlic Oil
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Are you ready for a marinade that’s absolutely, incredibly, insanely good? Because this flank steak marinade is unreal. We’re talking deeply savory, a little nutty, with just enough heat from the chili crisp and brightness from the lime — and then we pour a hot garlic green onion oil on top of the whole thing.
Flank steak is one of my favorite cuts to work with because it’s lean, high in protein, and soaks up a marinade better than almost anything else. Give it at least a couple hours, overnight if you can swing it and you’re ready to go.
Best part? No fancy techniques, no complicated steps. Just a marinade you’ll want to drink (probably shouldn’t tho, kinda weird). Try it paired with Air Fryer Twice Baked Potatoes and this amazing Snap Pea Salad.
Why you’ll love this recipe
- High-protein, perfect for macro counters
- Marinade is to die for
- Green onion sauce is absolute fire
- Perfect for meal prep
Ingredients and Substitutions:
These are the main ingredients and substitutions for this flank steak marinade. See the recipe card below for the full ingredient list and instructions.
Flank Steak: The star of the show. Flank steak is a lean, high-protein cut that’s perfect for marinating because it absorbs flavor like a sponge. Look for a piece that’s as uniform in thickness as possible so it cooks evenly on the grill.
Fish Sauce: Don’t skip this one and don’t be scared of it. Fish sauce adds this deep, savory, umami richness that you can’t quite put your finger on — you won’t taste “fish,” you’ll just taste more. It’s the ingredient that makes people ask what your secret is.
Tahini: This is what makes this marinade different from every other flank steak marinade out there. Tahini adds a subtle nuttiness and a little body that makes the marinade cling to the meat. Trust it.
Soy Sauce: Your salty, savory base. It works together with the fish sauce to build that deep flavor foundation.
Rice Wine Vinegar: The acid in the marinade. Acid is what actually tenderizes the meat, breaking down the muscle fibers so the steak comes out juicy and not chewy.
Toasted Sesame Oil: Nutty, aromatic, and a little goes a long way. This is a finishing flavor — it rounds everything out beautifully.
Honey: Balances out all that savory and helps the outside of the steak caramelize on the grill. That char? Honey’s doing that.
Garlic + Fresh Ginger: Non-negotiable. Fresh is always better here — the flavor is brighter and more vibrant than powder.
Chili Crisp or Sambal: Your heat element. Chili crisp adds a little crunch and complexity, sambal is a bit more straightforward — either works great. Adjust to your spice preference.
Lime Juice: A squeeze of fresh lime at the end brightens the whole marinade and keeps it from feeling heavy.
Dietary Modifications
- This recipe is dairy-free, as is.
- For gluten-free sub soy sauce for coconut aminos or tamari and be sure your fish sauce is certified GF.
Tips on how to make the perfect flank steak with this marinade
- Marinate as long as you can. Two hours is the minimum and you’ll still get great flavor, but overnight is where this marinade really shines.
- High heat only. Flank steak needs to cook fast over high heat to get that caramelized crust on the outside while staying juicy on the inside.
- Move to indirect heat if your steak is thick. If your flank steak is on the thicker side and needs more time to cook through, move it to indirect heat rather than leaving it over direct flame. This way you can finish cooking it without burning the outside.
- Let it rest — seriously. I know it smells incredible and you want to cut into it immediately. Don’t. Let the steak rest for 5–10 minutes after it comes off the grill.
- Always slice against the grain. This is the most important tip on this entire list. Flank steak has long muscle fibers that run in one direction — if you slice with those fibers, you’re biting through long tough strands of meat. If you slice against them, you’re cutting those fibers short, which makes every single bite tender and easy to chew.
- Make the sauce while the steak rests. The timing works out perfectly — the steak needs 5–10 minutes to rest anyway, so use that time to slice your green onions, mince your garlic, and heat your olive oil.
How to serve this flank steak for meal prep
You did the classic steak and potatoes and now you have leftovers. How lucky you are.
- Steak bowls — slice over rice or turkey rice bowls (swap turkey for the steak).
- Steak tacos — warm tortillas, sliced steak, avocado, and a squeeze of lime. Use low-carb tortillas to keep the carbs in check.
- Salads — throw sliced steak over a simple green salad for an easy high-protein lunch
- Steak and eggs — leftover steak reheated alongside eggs is one of the best high-protein breakfasts you can make
How to store leftover flank steak
Leftover flank steak will keep in an airtight container in the fridge for up to 4 days. Slice it before storing so it’s ready to grab and go and you’ll thank yourself later. When reheating, go low and slow in a pan with a tiny splash of water or a quick zap in the microwave. The green onion oil heats perfectly fine.
Recipe FAQs
At least 2 hours, but overnight is where the magic happens. The longer the steak sits in the marinade, the more tender and flavorful it gets. Don’t go beyond 24 hours or the acid can start to break down the texture.
Fish sauce adds deep, savory umami flavor without tasting “fishy” at all — it’s one of those background ingredients that makes everything taste more complex and rich. It’s a secret weapon in this marinade.
Always slice against the grain — this shortens the muscle fibers and makes the steak melt in your mouth instead of feeling chewy. If you slice with the grain, even a perfectly cooked steak will be tough. Please for the love of cooking, SLICE AGAINST THE GRAIN!
Yes — a cast iron grill pan on high heat works great. You’ll still get a good sear. Cook 4–7 minutes per side depending on thickness. Try my cast iron flank steak for an indoor version.
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Flank Steak Marinade
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Ingredients
- 2.5 lbs. flank steak
- 3 Tbsp. fish sauce
- 2 Tbsp. tahini
- 3 Tbsp. soy sauce
- 2 Tbsp. rice wine vinegar
- 1 Tbsp. honey
- 5 cloves garlic, minced
- 1 Tbsp. fresh ginger, grated
- 2 tsp. chili crisp or sambal
Green Onion Garlic Sauce
- 4 green onions, thinly sliced
- 3 cloves garlic minced
- pinch of salt
- 1 tsp. soy sauce
- 2 Tbsp. olive oil
- optional: tiny pinch of red pepper flakes
Instructions
- Add the fish sauce, tahini, soy sauce, rice wine vinegar, toasted sesame oil, honey, garlic, ginger, and chili crisp to a large zip lock bag. Seal and shake to combine well. Add the flank steak directly to the bag. Massage to get fully covered and place in the refrigerator to marinate for at least 2 hours or overnight. Flip the bag every so often to ensure everything gets soaked.
- When ready to cook heat the BBQ or grill pan to high heat. Place the meat directly on the BBQ and cook for 4-7 minutes per side. If you need to cook longer due to the thickness move to indirect heat so it doesn't burn.
- Remove and let the meat rest for 5-10 minutes while you prep the sauce.
- Add the green onions, garlic, salt and soy sauce to a small bowl. Heat the olive oil in a small sauce pan until hot and bubbly or almost smoking. Pour over the green onion mixture and enjoy the smell. Mix.
- Slice the meat AGAINST the grain not with the grain. Plate and pour the green onion sauce on top.
Notes
- Nutritional information is an estimate and will vary with substitutions.
- The tossed marinade from the steak has been accounted for in the nutritional information.
- Please cut the meat AGAINST the grain not with the grain.
- Let the meat marinate for at least 2 hours. Overnight is best!
- Cook on the BBQ, indoor grill pan or a cast iron.
