To make tomatillo salsa, preheat broiler. Place tomatillos, jalapeño, and garlic on a sheet pan, leaving skins on the tomatillos and garlic.
Broil for 5 minutes or until charred. Remove and allow to cool.
Once cooled, remove skins from tomatillos and garlic.
Halve the jalapeño and remove seeds.
Add tomatillos, garlic, jalapeño, canned green chiles, cilantro, juice from one lime and salt to a blender. Blend until smooth and combined. Pour into a bowl and set aside.
Preheat oven to 425F. Place sweet potatoes wedges and cauliflower florets into a large bowl and toss evenly with olive oil, chili pepper, cumin, salt, and black pepper.
Spread the wedges and florets out onto two baking sheets in an even layer.
Bake for 15-20 minutes, flip vegetables and bake for an additional 5 minutes or until tender and crisp. Remove from oven.
Using an oven-safe dish, create layers of nachos starting with chips, cheese, roasted vegetables, salsa, black beans, cheese again, chips etc. Add a final layer of cheese on top. Broil until bubbly and melted.
Before serving, top with additional salsa, guacamole, sour cream, cilantro, green onions and queso fresco. Squeeze a little lime juice right before serving.