Mix the sugar, chili powder, ketchup, water, soy sauce, vinegar, and Worcestershire sauce and stir. Pour the mixture over the brisket and vegetables. Cover tight with heavy tin foil. Cook for 3 to 4 hours. After the brisket has been in the oven for 2 to 3 hours, take out and add crumbled the ginger snap cookies into the liquid that surrounds the brisket. Mix around so the sauce gets thicker. Put back in oven, uncovered, for the remaining 1 hour.
When the cooking is complete, take out of oven and let rest for 1 hour. Slice thin and put in the refrigerator overnight.
Reheat and serve the next day.
For the sandwich: Toast the light rye bread. Place the cheese on one slice of bread and melt in microwave. Spread the caramelized onions on top of the melted cheese. Put sliced brisket on top of the onions. Top with coleslaw, then with pickles and the other slice of bread.