Combine all the marinade ingredients in a bowl and add the chicken. Refrigerate overnight.
Preheat the oven to 400F.
Heat a cast iron skillet (or non-stick skillet) over medium heat and cook the chicken 5-7 minutes per side for thighs, 8-10 minutes for breasts, until browned and cooked through. Internal temperature should be 165F when done.
Remove from heat, let cool and chop into bite sized pieces.
While the chicken is cooling, pour the coconut milk, salt and curry paste into a sauce pan and heat to boiling to make the Thai yellow curry sauce. Simmer for 5 minutes, remove from heat and set aside.
Add the diced sweet potato to the skillet and cook on medium until lightly browned and caramelized, about 7 minutes.
Place the flatbread on a baking sheet. Spread a layer sauce (about 2 heaping tablespoons) over each flatbread.
Add the sliced chicken, sweet potato, red peppers, sliced onions and cashews.
Slice the mozzarella into thin slices and place 2-3 slices on each flatbread. Drizzle each flatbread with about 1 tablespoon of the sauce.
Bake the flatbread for 15 minutes, or until cheese is melted, bubbly, and starting to lightly brown.
Remove from oven and let cool for 5-10 minutes before slicing. Cut it using a pizza cutter and garnish with fresh cilantro. Serve with extra sauce for dipping if desired.