Slow Cooker Chicken Fajita Soup

Name: Slow Cooker Chicken Fajita Soup
Ingredients: * 1 pound chicken breast, cubed; * 1/2 yellow onion, chopped (175 gram); * 2 pepper, chopped (370 gram); * 1 can diced tomato (14.5 ounce); * 1 cup white or brown rice (not cooked); * 1 1/2 cup black bean; * 5 cup packed kale, roughly chopped; * 32 ounce low sodium chicken broth; * 1 1/2 teaspoon garlic powder; * 1 1/2 teaspoon cumin; * 1 teaspoon chili powder; * 1/2 teaspoon cayenne pepper; * 1/2 teaspoon red pepper flake; * salt and pepper, to taste; * optional topping: tortilla chip, avocado guacamole, cilantro, diced