1-First Step: Make Chimichurri Sauce Grab a bowl and toss in 1 cup finely chopped fresh parsley, 1/4 cup chopped cilantro, 3 minced garlic cloves, 1 tablespoon fresh oregano (or 1 teaspoon dried), and 1/2 teaspoon red pepper flakes if you crave heat. Pour in 1/4 cup red wine vinegar and 1/2 cup olive oil, then season with salt and pepper. Stir vigorously until it emulsifies into a vibrant green elixir. Let it sit for 30 minutes to 4 hours in the fridge, allowing flavors to dance and deepen. This sauce is the heartbeat of your dish, tangy and aromatic.

2-Second Step: Marinate Steak Pat your 1-pound flank, skirt, or sirloin steak dry, season both sides generously with salt and pepper. Spoon a few tablespoons of chimichurri over it, rubbing to coat every inch. Slide into the fridge for 30 minutes to 4 hours. Feel the marinade tenderizing the meat, infusing it with garlicky, herby essence. Longer marination amps up flavor without overpowering.

3-Third Step: Grill Steak Fire up your grill to medium-high heat, around 400-450°F, for perfect sear marks. Place the steak on the grates and grill 4-5 minutes per side for medium-rare (135°F internal). Listen to the hiss as juices caramelize. Remove and rest 5-10 minutes under foil, then slice thinly against the grain. Those thin strips ensure tenderness in every quesadilla bite. For indoor cooks, use a cast-iron skillet over high heat.

4-Fourth Step: Make Avocado Chimichurri Scoop out 1 ripe avocado and mash it smooth with a fork. Fold in 1/4 cup prepared chimichurri sauce and juice from 1/2 lime. Taste and adjust salt and pepper. The result? A velvety, cooling contrast to the spicy steak, with lime cutting any richness. Prep this just before assembly to keep it fresh and vibrant.

5-Final Step: Assemble and Cook Quesadilla Heat a skillet over medium heat with a touch of oil. Lay one 10-inch tortilla down, sprinkle half the 1 cup shredded Monterey Jack cheese, add 1/2 cup thinly sliced grilled steak, 1/4 cup avocado chimichurri, 1/4 cup sliced onion, and top with remaining cheese and second tortilla. Press gently. Cook 2-4 minutes per side until golden, crispy edges form and cheese oozes. Slice into wedges and serve hot, drizzling extra chimichurri. The onion’s bite pairs with melty cheese for pure bliss.