Preheat the oven to 375°F. Using a strong, sharp knife, carefully cut the squash(es) in half vertically and scoop out the seeds.
Rub the inside flesh of the spaghetti squash with 1 tablespoon olive oil and 1 teaspoon of salt. Place the cut sides down on a pan and roast for 12 minutes. Turn over so the cut side is facing up and bake for another 15-20 minutes or the until flesh is softened and will pull into strands when pierced with a fork. Be careful not to overcook. Remove from the oven, let cool slightly and use a fork to remove the strands. Divide equally among serving bowls.
While the squash is cooking, heat the remaining olive oil in a skillet over medium-low heat. Add the garlic, bell pepper, onion and 1 tsp of salt. Cook, stirring, for 3 to 4 minutes. Add the remaining 1 tsp of salt, chili powder, cumin, and black beans, stirring to coat. Cook for 4 minutes.
Add the black bean mixture on top of the spaghetti squash.
Mash the avocado with the lime juice and a few pinches of salt. Divide the avocado mixture and add on top of the black beans. Top with salsa and hot sauce (optional)!