Step 1: Prepare the Steak. In a medium bowl, toss the thinly sliced steak with 1 tablespoon olive oil, chili powder, cumin, garlic powder, salt, and pepper. Set aside.
Step 2: Cook the Steak. Heat a large skillet or grill pan over medium-high heat. Add the seasoned steak and cook for 2-3 minutes per side, or until cooked to your desired doneness. Remove from skillet and set aside.
Step 3: Prepare the Shrimp. In the same bowl (no need to clean), toss the peeled and deveined shrimp with 1 tablespoon olive oil, smoked paprika, cayenne pepper (if using), salt, and pepper.
Step 4: Cook the Shrimp. In the same skillet, add the seasoned shrimp and cook for 2-3 minutes per side, until pink and opaque. Remove from skillet and set aside.
Step 5: Assemble the Nachos. Preheat your oven to 375°F (190°C). Arrange half of the tortilla chips in a single layer on a large baking sheet. Sprinkle with half of the Monterey Jack and cheddar cheeses. Top with half of the cooked steak, shrimp, red onion, red bell pepper, and green bell pepper.
Step 6: Bake the Nachos. Repeat the layering process with the remaining chips, cheeses, steak, shrimp, and vegetables. Place the baking sheet in the preheated oven and bake for 10-15 minutes, or until the cheese is melted and bubbly and the chips are slightly golden.
Step 7: Garnish and Serve. Carefully remove the nachos from the oven. Garnish generously with fresh cilantro, pickled jalapeños, dollops of sour cream, avocado slices or guacamole, and a side of salsa. Serve immediately and enjoy!