Cut lamb into 2 inch cubes, removing any fat. Reserve any
trimmings for browning meat.
Combine flour, paprika and onion powder and add to meat and toss until coated.
Heat lamb fat trimmings in a large skillet to render fat. Add oil, if needed, to measure 2 tablespoons and brown meat well.
Meanwhile, combine Kahlua, water, vinegar, garlic, salt, rosemary and pepper. When meat is browned, discard any fat remaining in skillet. Add Kahlua mixture to meat. Bring to boil, cover and turn heat low. Simmer 1 1/2 to 1 3/4 hours, or until meat is tender. Cut mushrooms in halves and add to the skillet in last 5 minutes as meat cooks.
Remove lamb and mushrooms to heated serving platter. Skim off any excess fat from sauce. Pour over the lamb, or serve on the side. Garnish with sliced green onion and lemon wedges. Serve with rice, if desired.
