In stockpot heat reserved bacon fat. Add onions, salt and pepper and cook until onions turn a deep brown, about 10 to 15 minutes. Add chicken stock and simmer for 15 minutes. Skim and discard fat from the top and bring broth to a boil. Stir in fried bacon and the tomatoes. Return to a boil. Gently stir in beaten eggs, until cooked and thready, about 1 to 2 minutes, being careful not to overblend. Remove pot from heat.