Sausage in Beer Mustard Sauce

2 pounds Polish or smoked sausage
1 large onion, quartered and sliced 1/2 inch
2/3 cup beer
1/3 cup brown sugar
1/4 cup vinegar
1/4 cup prepared mustard
1 tablespoon cornstarch mixed with 2 teaspoons water to make a paste

Slice sausage into 1 inch rounds; place in crockpot along with the onion.

Combine remaining ingredients and pour over sausage and onions.

Cover and cook on low for 6 to 8 hours; stir in cornstarch water paste to thicken before serving, if desired.

Serve with potato salad, rice, or noodles.

Serves 6.