How to Cook a Flank Steak on a Gas Grill (Step-by-Step Guide)

Flank steak is one of the most flavorful cuts of beef you can buy, but it does require a little knowledge and care to cook properly. Because it’s a lean and fibrous cut, it can easily turn dry and tough if you treat it like a ribeye or New York strip. That said, when cooked correctly especially over the open flame of a gas grill flank steak becomes juicy, incredibly tender, and full of bold, beefy flavor.

In this in-depth guide, you’ll learn exactly how to cook flank steak on a gas grill from start to finish, including how to choose the right cut, how to marinate it for maximum tenderness, what grill temperature to use, and how to slice it so it’s melt-in-your-mouth delicious.

What Is Flank Steak and Why Grill It?

Flank steak comes from the lower abdominal area of the cow. It’s a long, flat, and somewhat coarse-grained muscle, which is why it’s naturally lean and full of strong connective tissue. Unlike ribeye or strip steaks, it doesn’t have a lot of marbling, but what it does have is deep beef flavor.

Grilling is one of the best ways to cook flank steak because the high heat lightly chars the outside while keeping the inside juicy. This creates a perfect contrast in flavor and texture especially when paired with a good marinade and sliced correctly.

Choosing the Right Flank Steak

Not all flank steaks are created equal. To get the best result on the grill, look for the following characteristics:

• Bright red color with no gray spots
• Uniform thickness (at least ¾–1 inch thick)
• Visible muscle grain, but not excessive fat or membrane
• Some marbling is fine — but avoid pieces that have thick, hard fat strips

💡 Tip: Grass-fed flank steaks tend to have a more intense beef flavor, while grain-fed flank steaks are slightly milder but more tender.

Try to select a piece that is around 1½ to 2 pounds, which feeds 3–4 people and cooks evenly on a gas grill.

Preparing the Flank Steak

A. Trim Off Excess Silver Skin

Most flank steaks are already trimmed, but if you see tough pieces of silver skin on the surface, use a sharp knife to carefully scrape them off — they don’t break down and can make bites chewy.

B. Marinate the Steak for Tenderness

Flank steak should always be marinated. The acid in the marinade helps break down the connective tissue and allows flavors to soak into the meat.

Here’s a classic flank steak marinade to use (you can tweak ingredients to taste):

Ingredient	Amount
Olive oil	¼ cup
Soy sauce	¼ cup
Fresh garlic (minced)	2–3 cloves
Lemon juice or vinegar	2 tbsp
Honey or brown sugar	1 tbsp
Black pepper	1 tsp

Mix all ingredients and place the steak in a zip-top bag or shallow dish. Pour over the marinade, making sure the entire surface is coated.
Marinate for at least 1 hour (minimum), but ideally 6–8 hours in the refrigerator.

⚠️ Don’t exceed 12 hours, or the acid can begin to “cook” the meat and change its texture.

Approximately 30–45 minutes before grilling, remove the steak from the refrigerator and let it come to room temperature while still in the marinade. This ensures even cooking.

Prepping the Gas Grill

Setting up your grill properly is just as important as preparing the steak.

1. Clean the grates (use a wire brush if necessary).
2. Oil the grates lightly with a high-heat oil (canola, avocado) to prevent sticking.
3. Preheat the grill on high heat for 10–15 minutes.
   Your target temperature is 450–500°F directly over the burners.

Flank steak requires high heat for a short period to sear the outside without drying out the inside.

Grilling the Flank Steak Over Direct Heat

A. Sear Both Sides

Place the steak directly over the hottest part of the grill.
Do not close the lid right away — let the outside develop a crust.

• Grill for 3–4 minutes on the first side.
• Flip with tongs and grill for 3–4 minutes on the other side.

B. Check Internal Temperature

For best results, flank steak should be cooked to medium-rare (130–135°F).
Insert an instant-read meat thermometer in the thickest part of the steak:

Doneness	Internal Temp
Rare	120–125°F
Medium-rare	130–135°F
Medium	140–145°F

If your steak has not yet reached your target temperature after 8 total minutes, move it to indirect heat (a cooler zone of the grill) and close the lid for another 1–2 minutes.

⚠️ Avoid cooking flank steak to medium-well or well-done — it will become dry and chewy.

Resting and Slicing the Flank Steak

Let It Rest

Transfer the steak to a cutting board and let it rest for 5–10 minutes. This allows the juices to redistribute through the meat and prevents them from spilling out when sliced.

Slice Against the Grain

Lay the steak flat and identify the direction of the muscle fibers (you’ll see long lines running across the surface).
Use a sharp knife and slice perpendicular to those lines — this shortens the muscle fibers and makes the steak much more tender.

Ideal slice thickness: ¼ inch

✏️ Tip: If you want extra tenderness, slice diagonally with a slight bias rather than straight down.

Serving Suggestions

The beauty of flank steak is how versatile it is. Here are a few serving ideas:

Style	Description
Classic	Drizzle with chimichurri or garlic herb butter
Fajitas	Slice into strips and serve with sautéed peppers/onions
Salad	Add slices to a bed of mixed greens with vinaigrette
BBQ Platter	Pair with roasted potatoes and grilled corn

You can also refrigerate leftovers and use them in wraps or tacos over the next day or two.

Tips & Common Mistakes to Avoid

✅ Do marinate — it’s essential for tenderness
❌ Don’t overcook — high heat + short time is key
✅ Always slice against the grain
❌ Don’t skip resting — the steak will dry out
✅ Oil the grill grates to prevent sticking
❌ Don’t use a fork to flip the steak — it will pierce the meat and let juices escape

Final Thoughts

Cooking flank steak on a gas grill is simple once you understand the key steps: marinate, grill hot and fast, and slice properly. Because this cut is lean and tightly grained, every one of these steps helps transform it into a tender and flavorful meal that rivals more expensive cuts.

If you follow the method above from choosing a good steak to resting and slicing it properly you’ll end up with perfectly juicy flank steak every time.