In a medium bowl, combine the black beans, lime juice, taco seasoning, 1 teaspoon of olive oil, and salt. Mix well and set aside to marinate.

Heat 2 teaspoons of olive oil in a large skillet over medium heat. Add the sliced red bell peppers, a pinch of salt, and pepper to taste. Cook for 8-10 minutes until the peppers are soft and slightly caramelized. Remove from heat.

To assemble the burritos, lay out the flour tortillas and add a layer of spinach or lettuce in the center of each. Top with a scoop of rice, marinated black beans, sautéed peppers, guacamole, pickled red onions, cilantro leaves, and jalapeño slices if using.

Fold the sides of the tortilla inwards, then roll up tightly from the bottom to enclose the filling. Serve with salsa on the side.