Seared Flank Steak Sweet Onion Quesadilla

Quesadillas grew from Mexican tortilla traditions into a Tex-Mex favorite built for sharing. This one layers seared flank steak and deeply caramelized sweet onions with melted Jack and cheddar for a savory, golden fold.

Serves 4 · 20 min prep · 40 min cook

Estimate for one serving

• 620 cal
• 38g protein
• 42g carbs
• 34g fat
• 3g fiber

Every recipe here is free to read.

Ingredients

• 1 lb flank steak
• 2 large yellow onions
• 4 flour tortillas (10-inch)
• 2 cups shredded Monterey Jack cheese
• 1 cup shredded sharp cheddar cheese
• 3 tbsp olive oil
• 2 tbsp unsalted butter
• 1 tsp garlic powder
• 1 tsp smoked paprika
• 1.5 tsp kosher salt
• 1 tsp black pepper
• 1/4 cup fresh cilantro leaves
• 3 tbsp toasted pepitas
• 1 lime lime wedges

Instructions

1. 1Pat the flank steak dry and season both sides generously with salt, black pepper, garlic powder, and smoked paprika. Let it sit at room temperature for 10 minutes while you prep the onions.
2. 2Slice the onions into thin half-moons. Heat one tablespoon of olive oil and one tablespoon of butter in a large skillet over medium heat until the butter foams.
3. 3Add the onions and salt. Cook, stirring every few minutes, for 18 to 22 minutes until deeply golden and sweet; lower the heat if they threaten to burn and add a splash of water if the pan dries out. Transfer caramelized onions to a bowl.
4. 4Wipe the skillet, raise heat to medium-high, and add the remaining olive oil. Sear the steak 3 to 4 minutes per side for medium-rare, or until an instant-read thermometer hits 130°F. Rest the steak on a cutting board for 5 minutes.
5. 5Slice the rested steak thinly against the grain into bite-size strips.
6. 6Wipe the skillet clean again and set it over medium heat. Place one tortilla in the dry pan for 20 seconds to warm, then flip.
7. 7Scatter a mix of Monterey Jack and cheddar over half the tortilla, top with steak strips, a generous spoonful of caramelized onions, a few cilantro leaves, and a sprinkle of pepitas. Fold the empty half over the filling and press gently with a spatula.
8. 8Cook 2 to 3 minutes until the underside is deep golden and crisp, then carefully flip and cook another 2 to 3 minutes until cheese is fully melted and stretchy. Repeat with remaining tortillas, adding a thin smear of butter to the pan between batches if needed.
9. 9Transfer each quesadilla to a cutting board, rest 1 minute so the cheese sets slightly, then slice into wedges. Serve immediately with lime wedges for squeezing.