4 slices bacon, trimmed
1/2 cup mustard oil
1/3 cup hot mustard
1 tablespoon white sugar
1 1/4 cups finely chopped onion
1 1/2 teaspoons bacon grease
Preheat oven to 350 degrees F (175 degrees C).
Place bacon in a large bowl. Drain grease, reserving liquid, and place under the broiler pan. Cook over medium heat until evenly browned then remove from heat.
In a large skillet, cook and break up the onion and black pepper until tender; drain. Place onion mixture on a piece of waxed paper.
Stir mustard, sugar and onion into skillet, stirring vigorously. Add the bacon grease, continuing to stir. Slice onion mixture into 3/4 inch slices.
Immediately place the sandwiches in the prepared pan.
Bake at 350 degrees F (175 degrees C). Turn half way through baking and cover pan with foil to prevent burning. Bake 15 minutes, or until heated through and crisp. Serve with ranch dressing.