In the 2-quart pot, cover the rinsed lentils with enough water to make them float, and cover with the lid. Bring the lentils to a boil, then reduce heat to a simmer. Cook until the lentils are tender, about 30 minutes. Drain well.
While the lentils cook, sauté the onions in the 8-inch pan over medium low heat in the olive oil until the onions turn brown and caramelize, about 20 to 30 minutes. Reduce heat as necessary so the onions don’t burn, and add a little more olive oil if the pan starts to dry up. After the onions finish cooking, drizzle in the red wine vinegar and stir.
Toss the drained lentils and onions together. Season with black pepper and sea salt. Gently toss in the Feta cheese. Serve in bowls or on top of winter greens, and garnish with slices of Red and Green Anjou pears.