Prepare bratwurst according to package directions; cut cooked sausage into ¼-inch slices.
Spread 5 tortillas with mustard.
Top with 2 cheese slices, sausage slices, pickle and onion.
Top with an additional 2 slices of cheese and cover with another tortilla.
Press down slightly on top tortilla to marry the ingredients together.
Grill over medium heat on outdoor grill, indoor grill pan or in the oven until warmed through.
Slice into wedges and serve immediately.