01 - Preheat the oven to 375°F.
02 - Heat olive oil in a large skillet over medium heat. Add onion and cook until softened, approximately 3 minutes. Stir in garlic and cook an additional minute.
03 - Add ground beef to the skillet and cook, breaking it apart, until browned, about 5 minutes. Drain excess fat if necessary.
04 - Mix in cumin, chili powder, smoked paprika, salt, and pepper. Incorporate tomato paste and water; simmer for 2 to 3 minutes until slightly thickened. Remove from heat.
05 - Spread tortilla chips evenly on a large baking sheet. Distribute beef mixture over chips, then sprinkle shredded cheddar and Monterey Jack cheeses on top.
06 - Bake in the preheated oven for 8 to 10 minutes, or until cheese is melted and bubbling.
07 - In a bowl, mash avocados until smooth with some texture remaining. Stir in diced tomato, red onion, lime juice, cilantro, salt, and pepper to taste.
08 - Combine diced tomatoes, red onion, jalapeño, cilantro, lime juice, and salt in a bowl. Mix thoroughly.
09 - Remove nachos from oven and top with dollops of guacamole and spoonfuls of fresh salsa. Add sour cream, sliced green onions, and fresh cilantro leaves as desired. Serve immediately.