About 2 hours before serving in 5-quart Dutch oven over medium-high heat in hot salad oil cook frankfurters until lightly browned on all sides stirring frequently
With slotted spoon remove frankfurters to bowl cover and refrigerate
In drippings remaining in Dutch oven over medium heat cook celery red pepper carrot onion and garlic until tender about 10 minutes stirring occasionally
Meanwhile rinse lentils in running cold water and discard any stones or shriveled lentils
Add lentils pepper bouillon 11 cups water and 1 teaspoon salt to vegetable mixture in Dutch oven
Over high heat heat to boiling
Reduce heat to low cover and simmer 1 hour or until lentils are very tender and soup has thickened
Return frankfurters to Dutch oven and cook until done