Step 1

In a small bowl toss sliced onion with vinegar and sprinkle with a pinch of salt. Set aside while you cook the lentils. (soaking will soften the onions and mellow their flavor)

Step 2

Bring 6 cups water to a boil in a medium saucepan. Add the lentils, reduce heat to a simmer and cook, partially covered, for 18-22 minutes or until lentils are cooked but not mushy. Check for doneness starting at 18 minutes. Drain and transfer lentils to a large bowl. While lentils are hot, toss with the olive oil (4 tablespoons), onions with their vinegar, garlic, 1 teaspoon of salt and black pepper, to taste. Stir and season with additional salt, if needed. (Salad can be made ahead to this point. See notes, below)

Step 3

Allow lentils to cool to room temperature and toss with herbs and feta. Serve at room temperature.