Sort and rinse the lentils. Place lentils and water in a heavy bottom soup pot. Bring to a boil. Turn heat to medium and cook just until tender, about 30 minutes. Place lentils in a colander to drain off excess water. Place cooked lentils in a large mixing bowl to cool. Once cool, toss the lentils with vinegar, sea salt and pepper. Set aside.
In a large sauté pan, heat 2 tablespoons olive oil on medium-high heat. Add the diced carrots, celery and yellow onion. Sauté with a good pinch of salt until tender, about 6-8 minutes. Add the cooked vegetables to the lentils. Stir in remaining ingredients. Season to taste with sherry vinegar, sea salt and pepper.
Variations to add to finished lentil salad:
½ cup diced cucumbers
½ cup crumbled goat cheese
2 tbsps fresh mint, chopped
1 cup halved heirloom cherry tomatoes