Combine ground meat, breadcrumbs, egg, onion, and seasonings in a bowl. Mix gently until just combined. Avoid overmixing.
Use a small ice cream scoop to portion the meatballs.
Brown the meatballs in a skillet over medium heat.
In the same skillet, combine cranberry sauce, chili sauce, and brown sugar. Bring to a simmer.
Add the browned meatballs to the sauce. Simmer gently over low heat for 20-25 minutes, or until the meatballs are cooked through and the sauce has thickened.
Taste and adjust seasonings as needed. Add more brown sugar for sweetness, chili sauce for heat, or a splash of orange juice for brightness.