Heat olive oil in a large skillet over medium heat.
Add diced onion, red bell pepper, and zucchini. Sauté for 5-7 minutes until veggies are tender.
Stir in garlic, cumin, chili powder, smoked paprika, salt, and pepper; cook for 1 minute until fragrant.
Add black beans and cook for 3-4 minutes until warmed through, stirring occasionally.
In a small bowl, mix sour cream with lime juice to create a tangy lime crema.
Warm the corn tortillas in a dry pan or microwave until pliable.
Assemble tacos by spooning the veggie and black bean mixture onto each tortilla.
Top with lime crema, sliced avocado, shredded cheddar (if using), and chopped cilantro.
Serve immediately and enjoy!