Toast sesame seeds in a dry frying pan over medium heat until fragrant and slightly browned, stirring occasionally.
Place seeds in a bowl with the green onions, ketchup, soy sauce, ginger, molasses, salt, curry powder, black pepper, 1 cup water, and wine vinegar. Stir to mix thoroughly.
Place meat in a slow cooker and pour the marinade over the meat. You can store in the refrigerator overnight. Cook on low for 8 to 9 hours or on high for about 3 hours.
Pour pan juices into a 2-cup measure. Skim off fat, returning 2 tablespoons of the fat to a pan. If the pan juices do not equal 2 cups, top off with water.
Whisk 3 tablespoons of flour into the fat in the pan and cook over medium heat on the stovetop until bubbly. Slowly stir in pan juices and cook until gravy thickens, stirring constantly.
Serve over noodles, rice, or mashed potatoes.