Preheat oven to 375°F. Heat oil in a large skillet over medium heat. Add red bell pepper and red onion, season generously with salt, and cook about 4-6 minutes, stirring occasionally, until vegetables soften but still have a little crunch. Add chicken, frozen corn, black beans, chilli powder, garlic powder, and cumin. Stir to combine and cook until everything is warmed through, about 2-3 minutes.
Roll out pizza dough pretty thin into a large rectangle-like shape and lay flat on a baking sheet lined with parchment paper. Scoop filling in a line down the middle of the pizza dough (leaving a little blank gap at either end) and top with pickled jalapenos and grated Castello Tickler Mature Cheddar cheese. Feel free to use more cheese if desired. Just like if you were making a burrito, bring the sides of the pizza dough together in the middle, overlapping to create a seal. Pinch either end and season top of dough with Kosher salt.
Cook in oven until crust is cooked through and golden brown, aboug 20-25 minutes. Remove from oven, let cool slightly, cut into slices and serve with sliced avocado, salsa, and sour cream.