Firm lentils are a beautiful thing; mushy lentils, not so much, unless you’re making soup. So, you need only boil them for 10 to 15 minutes for al dente. And after placing them in a strainer to drain, immediately rinse with cold water to stop them from cooking further.
Another thing to know about lentils is that they go a long way, so figure about 1/4 cup of dry lentils per person.
Ten minutes before your meal, heat some olive oil in a large pan and saute a minced shallot and a couple of cloves of garlic until translucent. Stir in the cooked lentils, a large handful of chopped arugula, some sunflower seeds or slivered almonds, and a generous grind of black pepper.
Cook for another five minutes, salt to taste and then serve with crumbled feta over the top.