Cook beef and garlic in skillet until lightly browned. Stir in pepper and thyme. Peel and slice potatoes and onions. Put 1/2 potatoes and onions into buttered crock pot. Add browned beef and top with remaining potatoes and onions. Mix mushroom soup with water and spread over top of contents. Cover. Cook on low for 8 to 10 hours or on high for 3 to 4 hours.