• Put broth and dried lentils into a large pot over high to medium heat.
• Saute the onions and garlic in 1 tablespoon of the oil till golden.
• If adding the optional cumin and curry, stir cumin and curry into the onions and cook a minute or two more.
• Stir onion mixture into the lentils.
• Saute the carrots and celery in the rest of the oil till just tender. Set aside.
• After lentils come to a full boil, reduce to simmer and simmer till lentils are tender. This will take anywhere from 1/2 hour to several hours depending on the type of lentils and the altitude. (Brown lentils in mile-high Albuquerque take us about 1-1/2 hours.) You will likely need to add additional water to lentils while they are cooking.
• After lentils are tender, stir in the cooked carrots and celery. Bring back to a boil but don't cook any more. (Don't overcook the carrots, don't want them to be mushy.)
• Season with salt and pepper to taste. (Don't add additional salt if broth is salty.)
• Spoon into bowls and add a dollup of yoghurt to each bowl.

Variations (not yet tried):

• Add diced potatoes along with the carrots and celery (per Andrew).
• Add 2 T. sauteed black mustard seeds (per Andrew).
• Add sauteed cumin seeds (per Andrew).
• Use lots more olive oil, up to 1 cup (per Andrew).