If you have the time - soak the lentils for about 4 hours - if not, just skip this step - but I would rinse them well.
In a large dutch oven or other heavy pan, heat the olive oil. Add the onions to the oil and lightly salt them. Saute for about 2-3 minutes until softened. Stir in the celery and carrots and saute for about 5 minutes, stirring frequently. Push the veggies aside and place the herbs in the oil - and let them saute for about 30 seconds.
Add the (drained) lentils and stir well to coat them in the oil.
Pour in the broth cover the pan and bring to a boil. Then bring to a low simmer (still covered) and heat for about 1 hour (not boiling - just a real low simmer). Taste for seasoning - add salt and pepper to taste. At this point I add the pastina, turn the heat off, and just let it sit for about 20 minutes or until the pastina is cooked. I sometimes add soup mac, I cook this separately and add just before serving - this prevents the macaroni from getting too inflated.