In a small bowl, whisk the garlic, brown sugar, soy sauce, sesame oil, ginger, Sriracha, and cornstarch. This is your stir-fry sauce. While prepping the sauce, sprinkle the chicken with ground black pepper.
In a skillet over medium-high heat, add one tablespoon of olive oil. Add the diced bell peppers and cook for 2 minutes until crisp-tender. Remove the bell peppers and set them aside on a plate.
Turn the heat to high and add the sliced chicken on one layer and cook on each side to sear the chicken reduce heat to medium-high and continue to cook until no longer pink and browned on each side.
Add the peppers back to the skillet with the chicken and pour the stir-fry sauce over. Simmer for 1-2 minutes until the sauce starts to thicken. If the sauce gets too thick, add a little water. Sprinkle with chopped cilantro and toasted sesame seeds. Serve the pepper chicken stir-fry over rice, rice noodles, or cauliflower rice.
