Prepare the ingredients: cut the chicken into bite-sized pieces. Dice the onion, cut bell peppers into 1-inch (1.5cm) cubes, finely chop the garlic.
Toss the chicken with Fajita seasoning, season with salt and pepper.
Heat the oil in a large pot over high heat, add the chicken in an even layer, don’t stir for the first 2 minutes letting the chicken brown. Stir the chicken and cook for 1-2 minutes, transfer to a plate. The chicken doesn’t have to be cooked, just browned. If you have a smaller pot, brown the chicken in two batches.
Heat the olive oil over medium heat, add the onion and bell peppers. Cook for about 5 minutes or until the onion is soft and translucent.
Add the garlic and cook for 30 seconds.
Add flour, cook, stirring for a minute.
Add diced tomatoes, chicken broth, and beans (and their liquid). Bring to a boil then simmer over low heat for 15 minutes.
Add the chicken back to the pot and cook for 1-2 minutes or until the chicken is cooked through.
Take the pot off the heat, season the soup with lime juice, salt, and pepper to taste.