1. Put the lentils in a medium saucepan with the water and 1/2 teaspoon of the salt. Bring to a boil. Reduce the heat to moderate and simmer, partially covered, until the lentils are tender, about 25 minutes. Drain and return to the pan. Add 1 tablespoon of the oil, 1 tablespoon of the vinegar, and 1/2 teaspoon of the salt. Mix gently and set aside.
2. Meanwhile, in a large nonstick frying pan, heat 3 tablespoons of the oil over moderately low heat. Add the onion and cook, stirring occasionally, until translucent, about 5 minutes. Add the carrots, celery, pepper, and 1 teaspoon of the salt. Cook, stirring occasionally, until the vegetables are tender, about 10 minutes. Remove from the heat and add 2 tablespoons of the vinegar. Combine the cooked lentils with the vegetables.
3. In a small frying pan, toast the almonds over moderately low heat, stirring frequently, until golden brown, 5 to 10 minutes. Or toast them in a 350° oven for 5 to 10 minutes. Shortly before serving, stir the almonds and parsley into the lentil mixture. Put the greens in a large glass or stainless-steel bowl and toss with the remaining 3 tablespoons oil, 1 tablespoon vinegar, and 1/2 teaspoon salt. Serve the lentil mixture over the greens.
Wine Recommendation: The unique earthy flavor of the lentils and the tangy vinaigrette call out for the delicate balance of sweet and tart found in a riesling kabinett from Germany's Mosel region.