Light Creamy Chicken Tortilla Soup

butter

olive oil

yellow onion (, diced)

garlic cloves (, minced)

((14-ounces) diced tomatoes, undrained)

carton ((32-ounces) chicken broth)

((16-ounces) refried beans)

ground cumin (, or to taste)

salt and fresh ground pepper (, to taste)

to 3 cups shredded cooked chicken ((leftover Rotisserie Chicken works great with this recipe))

canned corn kernels

Mexican Blend Shredded Cheese ((optional))

Avocado Slices ((optional))

Tortilla Strips ((optional))