Grilled Mustard-Marinated Flank Steak with Charred Scallions

By , Test Kitchen Director · Reviewed by AislePrompt Editorial · ·

A smoky grilled flank steak marinated in tangy Dijon mustard and herbs, served alongside sweet charred scallions for a hearty Father's Day main. This american-inspired bbq & smoked ready in about 30 minutes pairs pounds flank steak, Dijon mustard, olive oil for a weeknight-friendly dinner that comes together with one pan and minimal cleanup. Each serving lands at about 380 calories and feeds 4, so it slots cleanly into a weekly meal plan and pairs well with a quick salad or grain on the side. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.

Prep: 15 min Cook: 15 min Serves 4 American cuisine 380 cal/serving
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Ingredients

Instructions

  1. Step 1: In a medium bowl, whisk together 3 tablespoons Dijon mustard, 2 tablespoons olive oil, 3 minced garlic cloves, 1 tablespoon fresh thyme leaves, 1 teaspoon salt, and 1 teaspoon black pepper to create a marinade.
  2. Step 2: Place 1.5 pounds flank steak in a large resealable plastic bag and pour the marinade over it, massaging to coat thoroughly. Refrigerate and marinate for at least 2 hours or overnight.
  3. Step 3: Preheat grill to medium-high heat (about 400°F). Remove steak from marinade and let excess drip off.
  4. Step 4: Grill the flank steak for 4-5 minutes per side until medium-rare (internal temperature 130-135°F), turning once. Remove and let rest for 10 minutes.
  5. Step 5: While steak rests, place 8 whole scallions on the grill and cook for 3-4 minutes per side until tender and charred, turning occasionally.
  6. Step 6: Slice the steak thinly against the grain and drizzle with 1 tablespoon lemon juice. Serve with charred scallions alongside.

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Frequently asked questions

How long does Grilled Mustard-Marinated Flank Steak with Charred Scallions take to make?

Total time is about 30 minutes (15 min prep + 15 min cook). Most home cooks find this fits comfortably into a weeknight; double the batch on Sunday for two dinners.

How do I store leftover Grilled Mustard-Marinated Flank Steak with Charred Scallions?

Cool to room temperature within 2 hours, then store in an airtight container in the fridge for up to 4 days. Reheat covered in a 350°F oven for 10-12 minutes, or microwave at 70% power in 60-second bursts to keep pounds flank steak from drying out.

Can I substitute ingredients in Grilled Mustard-Marinated Flank Steak with Charred Scallions?

Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.

How do I scale Grilled Mustard-Marinated Flank Steak with Charred Scallions for a different number of people?

The recipe is written for 4 servings. Multiply each ingredient by (your serving target / 4). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.

What goes well with Grilled Mustard-Marinated Flank Steak with Charred Scallions?

American bbq & smoked like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.

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