Green Pepper & Tomato Meatball Skillet

Ingredients:

2½ oz. ground beef
¼ c. tomato puree
¼ tsp. ground coriander
2 tbsp. basil leaves
1 oz. mozzarella
½ tsp. dried oregano
1 oz. green bell pepper
½ tsp. garlic
1½ tbsp. butter
½ oz. red onion