In a saucepan over medium heat, melt the butter and olive oil together, then add the onion and sauté until lightly browned, about 5 to 7 minutes.
Reduce the temperature to low, add the garlic, catsup, brown sugar, lemon juice, Worcestershire, mustard, and Tabasco or hot sauce, and simmer for 10 minutes; add the shredded cooked meat, remove from heat, and set aside.
In a colander rinse the sauerkraut well under running water, then set aside to let drain.
In a lightly sprayed casserole dish, pour the meat and barbecue sauce mixture, then spread the sauerkraut over the meat.
In a bowl, combine the breadcrumbs and Parmesan.
Sprinkle crumb mixture over the sauerkraut, lightly spray with olive oil or pan spray, then bake at 350 degrees F for 20 to 25 minutes or until crumb topping is golden brown and crisped to desired texture.
Serve as is or over toast (dark rye is good!) or toasted hamburger buns.
Note: you can put a layer of barbecued beans under the shredded meat, if desired; also, you can use commercially prepared barbecued sauce instead of making your own as above (about 1 1/4 cup of sauce).