If using frozen meatballs be sure to simmer them for about 15 minutes before adding yogurt, to make sure they are fully thawed and warmed through.
- In large non-stick skillet, heat oil over medium heat and cook onion, garlic, ginger, curry powder, cumin and hot pepper flakes for about 4 minutes or until softened.
- Add ground cashews and stir to coat and cook for 1 minute.
- Add tomatoes and salt; bring to a simmer. Cook for 5 minutes.
- Add yogurt and butter and stir until butter is melted.
- Add meatballs, cover and simmer for about 5 minutes or until meatballs are heated through.