The sauce in these sandwiches may taste like an old family recipe that has been simmered for days, but the simple ingredients and short cooking time make it easy to whip up whenever you have a craving for barbecue.
Heat oil in saucepan over medium heat. Add onion, and sauté 7 minutes, or until soft. Add garlic, and cook 1 minute more.
Stir in tomato sauce, and cook 3 minutes. Add horseradish, molasses, vinegar, lemon zest and ½ cup water, and simmer over low heat 30 minutes, stirring occasionally. Fold in seitan.
Fill rolls with with barbecue mixture, and top with coleslaw, if desired. Serve with hot sauce.