Brown in a large nonstick skillet over medium-high heat for 5 min, breaking up the meat into crumbles as it cooks. Pour the drippings out of the pan and discard.
Add and cook 5 min, stirring occasionally.
Stir in the rest of the ingredients, reduce heat to low, and simmer for 5 min.
Place a half-cup scoop of the mixture onto each bun and serve.