Grilled Flat Iron Steak with Garlic Dijon Marinade

By AislePrompt Test Kitchen · Reviewed by AislePrompt Editorial · ·

Tender flat iron steak marinated in a zesty garlic and Dijon mustard blend, grilled to medium-rare perfection with a citrusy finish. This american-inspired beef ready in about 280 minutes blends pounds flat iron steak, tablespoons olive oil, tablespoons Dijon mustard into a versatile sauce that lifts everything from grain bowls and roasted vegetables to grilled proteins — a small-batch staple worth keeping in the fridge. Each serving lands at about 350 calories and feeds 4, so a small batch covers several meals across the week without taking over the fridge. 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: 270 min Cook: 10 min Serves 4 American cuisine 350 cal/serving
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Ingredients

Instructions

  1. Step 1: In a medium bowl, whisk together 3 tablespoons olive oil, 2 tablespoons Dijon mustard, 4 minced garlic cloves, 2 tablespoons lemon juice, 1 teaspoon fresh thyme leaves, 1 teaspoon salt, and 1/2 teaspoon black pepper until well combined and fragrant.
  2. Step 2: Place 1.5 pounds flat iron steak in a large resealable bag and pour the marinade over it, ensuring the steak is fully coated. Seal the bag and refrigerate for 4 hours to tenderize and infuse flavor.
  3. Step 3: Preheat your grill to high heat (about 450°F). Remove the steak from the marinade, letting excess drip off, and discard the marinade.
  4. Step 4: Grill the steak for 4-5 minutes per side for medium-rare, turning once, until a rich brown crust forms and the internal temperature reaches 130°F.
  5. Step 5: Transfer the steak to a cutting board, tent loosely with foil, and let rest for 5 minutes before slicing thinly against the grain to retain juiciness.

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Frequently asked questions

How long does Grilled Flat Iron Steak with Garlic Dijon Marinade take to make?

Total time is about 280 minutes (270 min prep + 10 min cook). A small batch typically covers several meals in the week — store as the recipe directs.

How do I store leftover Grilled Flat Iron Steak with Garlic Dijon Marinade?

Transfer to an airtight jar and refrigerate for up to 5–7 days. Most sauces freeze well for up to 2 months — portion into small containers or freezer bags so you can thaw only what you need. Stir before serving; cream- or yogurt-based sauces may separate on standing.

Can I substitute ingredients in Grilled Flat Iron Steak with Garlic Dijon Marinade?

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 Flat Iron Steak with Garlic Dijon Marinade 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 Flat Iron Steak with Garlic Dijon Marinade?

American beef 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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