Cut zucchini into 1/2" slices. Place in medium-large size saucepan. Add bone broth. Heat broth over high heat; then reduce heat to low and cover. Simmer zucchini 30 minutes.
Slice peppers thinly. Add peppers and chorizo to pot. Break up meat with a spatula into simmering broth. Mix peppers in as well. Continue to break up all meat into small pieces. Replace lid and simmer 20 minutes.
Stir the stew at this point, making sure all meat is broken up, allowing zucchini to break up and fall apart. Cook, covered, an additional 10 minutes over low heat, stirring occasionally.
Stir in butter, allowing it to melt and mix in completely. Serve.