Dice the Chicken breast, Slice the onion and bell peppers, mince the garlics.
Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the sliced onion and sauté until they are translucent, about 5 minutes.
Add Chicken breast to the same skillet, cook until the meat is browned, about 4-6 minutes.
Add sliced bell pepper and minced garlic, stir fry for about 1 minute.
Add smoked paprika, ground cumin, ground coriander, dried oregano, sugar, black pepper and salt, stir for 20 seconds.
Add 1 teaspoon of corn starch, and some cold water to a small drinking cup, mix well.
Add the starch water to the skillet, bring the content to boil, then reduce the heat to low, simmer for 5 minutes
Increase the heat to high, stir until the sauce in the skillet are thickened. The fajita is ready for assemble.