In a large mixing bowl, gently flake the drained tuna with a fork.
Add the rinsed and drained black beans and corn kernels to the bowl with the tuna.
Add the diced red bell pepper, finely diced red onion (if using), and minced jalapeño (if using) to the mixture.
In a separate small bowl, whisk together the lime juice, olive oil, ground cumin, chili powder (if using), minced garlic (if using), smoked paprika (if using), salt, and pepper until well combined.
Pour the dressing over the tuna mixture and fold gently to combine, being careful not to break up the tuna too much.
Add the fresh chopped cilantro and fold again until evenly distributed throughout the salad.
Gently fold in the cubed avocado last, using a light touch to prevent it from becoming mushy.
Taste and adjust seasonings as needed, adding more lime juice for brightness or salt for flavor.
Let the salad rest for 10-15 minutes before serving to allow the flavors to meld together.
Serve chilled or at room temperature.
