Favorite Lentils - adapted from Ina Garten (the Barefoot Contessa)

I was looking for a new lentil recipe when I stumbled across this gem from Ina Garten (a.k.a the Barefoot Contessa). Of all the Ina Garten recipes I've tried, I can't think of anything that hasn't been absolutely delicious. The lentils live up to Ina's reputation.

1⁄2 pound lentils
1⁄4 cup good olive oil
3 cups chopped yellow onions
1 teaspoon fresh thyme leaves (I used 1/2 tsp dry thyme)
2 teaspoons kosher salt
1/2 teaspoon freshly ground black pepper
1 tablespoon minced fresh garlic
1 1⁄2 cups chopped celery (4 stalks)
1 1⁄2 cups chopped carrots (3 carrots)
1 1⁄2 cups chicken stock or chicken broth (don't use bouillon cubes - the end result will be too salty)
2 tablespoons tomato paste
2 tablespoons good red wine vinegar

Place the lentils in a heat-proof bowl and cover with boiling water. Set aside for 15 minutes, then drain.

Meanwhile, heat the oil in a saute pan, add the onions, thyme, salt, and pepper and cook over medium heat for 10 minutes, until the onions are translucent. Add the garlic and cook for 2 more minutes. Add the drained lentils, celery, carrots, chicken stock, and tomato paste. Cover and simmer over low heat for 20 minutes, until the lentils are tender. Add the vinegar and season to taste. Enjoy!