French Dip Sandwich

5 lb boneless rump roast
1 Tbs garlic powder
1/2 tsp seasoned salt
1/4 tsp cayenne
1/2 tsp oregano
1/2 tsp rosemary
2 beef bouillon cubes
1 onion; chop fine
1 to 2 cans onion soup or beef broth
method:
Put all in slow cooker. Cook SLOW 8 to 10 hours or HIGH 4 to 6 hours.
If gravy is too thin mix cornstarch with some of gravy. Heat until thickened.
Slice thin and serve on French bread or French rolls.