1/4 cup chopped onion
1/4 cup butter or margarine
1 cup chili sauce
3/4 cup water
2 tablespoons vinegar
2 tablespoons brown sugar
1 teaspoon ground mustard
1 pound shaved fully cooked ham
8 hamburger buns, split

In a large saucepan or Dutch oven, saute onion in butter. Add chili sauce, water, vinegar, brown sugar and mustard; bring to a boil. Reduce heat; cover and simmer for 20 minutes.
Add ham; return to a boil. Reduce heat; cover and simmer for 10 minutes or until heated thrugh.

Spoon about 1/2 cup onto each bun.

Serves 8.