Finely chop the garlic to yield 2 tablespoons. Core, then coarsely chop the tomato(es) to yield 1 cup. Drain the roasted red bell peppers, then coarsely chop to yield 1 cup. Trim any excess fat from the chicken, then cut the chicken into bite-size pieces.
Heat the oil in a large skillet over medium-high heat until the oil shimmers. Stir in the garlic, fennel seed, cumin seed (crush them first, if desired) and the coriander; cook for 5 seconds, then add the chicken and cook for 5 minutes, stirring often. Season with salt and pepper to taste.
Add the tomato(es), roasted red bell peppers and Barney Butter; reduce the heat to low and stir to incorporate. Cover and cook for 3 to 5 minutes, or until the chicken has cooked through.