In a medium saucepan, combine the rinsed quinoa and water or broth. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes, or until the liquid is absorbed and the quinoa is fluffy. Remove from heat and let it sit, covered, for 5 minutes. Fluff with a fork.

While the quinoa cooks, heat the olive oil in a large skillet over medium heat. Add the diced onion and cook for 3-4 minutes until softened. Add the minced garlic, diced red bell pepper, cumin, chili powder, smoked paprika, and oregano. Cook, stirring frequently, for another 4-5 minutes until the peppers are tender.

Add the cooked quinoa, drained black beans, and corn kernels to the skillet with the sautéed vegetables. Increase the heat to medium-high. Cook, stirring constantly (stir-frying), for 4-5 minutes until everything is heated through and slightly crisped in places. Season generously with salt and pepper. Remove from heat and stir in the fresh lime juice and chopped cilantro.

While the filling rests for a minute, warm your tortillas. You can do this directly over a low gas flame for a few seconds per side, in a dry skillet, or wrapped in a damp towel and microwaved for 30 seconds. To assemble, place a warm tortilla on a plate. Add a layer of shredded lettuce, then a generous scoop of the quinoa and black bean filling. Top with avocado slices or guacamole, pico de gallo, and optional cheese or cream.

Serve the tacos immediately with lime wedges on the side for squeezing over the top. Arrange two tacos per plate for a beautiful presentation.