In a food processor, combine half the beans and half of the tomatoes and process until smooth. Set aside. Heat olive oil in a large pot over medium-high heat. Add onions to the pot and cook, stirring, until onions begin to soften, about 2 to 3 minutes. Add red and yellow peppers, stirring, for an additional 2 minutes, then the garlic, softening for a minute or so. Add the chilli element and cumin and stir for 20 seconds. Add chicken stock and stir for 3 to 4 minutes. Add the remaining beans, tomatoes, and the pureed bean mixture to the pot and bring to a boil. Stir in the chicken. Cover, reduce the heat to medium-low and simmer for 15 to 20 minutes so the flavours mix together. Stir in the coriander, lime juice, and season with salt and pepper to taste.
To make the avocado topping,: toss the avocado, lime juice, and coriander together in a small bowl, seasoning to taste. Serve immediately with a generous spoonful of the avocado garnish, or any other topping of your choice, such as a cooling half fat creme fraiche laced with fresh coriander.