Preheat oven to 400 degrees Fahrenheit. Line a baking sheet with parchment paper. Place handfuls of chips on the baking sheet and distribute evenly, minimizing the gaps between chips. Set aside.
Sprinkle the prepared pan of chips generously and evenly with the beans, followed by the shredded cheese, bell pepper, crumbled feta and pickled jalapeños (use more if you really love jalapeños, less if you don’t). Bake until the cheese is melted and bubbling, about 9 to 13 minutes. Remove the nachos from the oven and set aside.
While the nachos are baking, make the avocado sauce and prepare the garnishes.
Once the nachos are out of the oven, drizzle avocado sauce on top as shown—any extra can be served on the side. (If using guacamole instead, dollop the guacamole over the nachos like polka dots.) Sprinkle the nachos with chopped green onion, radish and cilantro. Serve immediately, with salsa on the side.