The Frosty Mug restaurant was in Monticello Indiana. I worked there when it was called The Tree House. The Kretchmar's guarded most of the recipe and would not let many know. Ruth and Bill made me swear not to tell anyone with was in their recipes. After they sold the restaurant Ruth published some of the guarded recipe in a local cookbook

Ingredients

96 ounces of ketsup

3 Cups yellow mustard

3 Cup white sugar

2 1/2 Cups white vinegar

1/2 Cup water

1/2 Cup barbecue sauce

1/3 Cup salt

3 Tablespoons Worcestershire sauce

1 Tablespoon celery seed

1 Tablespoon Tabasco sauce

5 Pounds ground chuck

1 Large white onion chopped, about a cup

Directions

Step 1: Mix all ingredients (except the hamburger meat and onions) thoroughly and put in five one-quart containers. Saute onion in butter for several minutes at medium temperature until clear. Add hamburger or ground chuck and salt to taste. As it cooks, smash large pieces with a potato masher. Stir frequently until it is done. Pour off excess fat immediately. Tip the pan to the point where you most of the fat has been drained. Add 1 quart of sauce for five lbs. of meat. Simmer slowly at least 30 minutes. Makes enough for 24 sandwiches.