Set a skillet over medium heat, about 5 out of 10, and cook the ground beef with the diced onion for 8 to 10 minutes. Use a wooden spoon to press and break the meat into small crumbles, scraping and turning every minute so it cooks evenly. You’ll see the beef lose its pink color and the onion soften. Stir in the taco seasoning and water, then let it simmer for 3 to 4 minutes. Move the spoon in slow circles so the liquid reduces evenly. The mixture should look glossy and lightly saucy, and you’ll smell the spices open up. If you rush this, the seasoning stays gritty and the beef tastes flat.

Lower the heat to medium-low, about 4 out of 10, and add the black beans. Use a wide spatula to fold from the bottom up for 2 to 3 minutes instead of stirring fast. This keeps the beans whole and coated. You’ll notice the mixture look fuller and slightly thicker as it warms through. The beans should stay intact with a light coating of sauce. If you overmix, they break apart and the filling turns too soft.

Preheat your oven to 375°F. Spread the chips across a baking sheet in a loose, even layer. Spoon the hot beef mixture over them using small scoops, then move your hand side to side so the topping spreads without piling. Scatter the cheeses over the top in a light, uneven layer. Aim for coverage but leave some chip edges visible. You should see layers of chips, beef, and cheese. If you overload one spot, it bakes unevenly and some chips turn soggy.

Place the pan in a 375°F oven and bake for 8 to 10 minutes. At minute 6, rotate the pan once so the heat hits evenly across the surface. This keeps one side from overcooking. Watch for the cheese to fully melt and bubble, with a few light golden spots. You’ll hear a soft sizzle and smell toasted cheese. Pull it right then. Leave it too long and the chips darken and lose their crunch. (I used to leave it longer for more color, but the chips always came out too hard.)

Let the nachos rest for 2 minutes after baking so the cheese sets slightly. Then scatter the tomatoes, jalapenos, and green onions using quick pinches so they spread evenly. Add small spoonfuls of sour cream and guacamole across the top instead of spreading them. Finish with cilantro. You’ll see the bright contrast over the melted cheese. If you add these too early, they wilt and lose their fresh bite.