Sauteed Bacon, Mushrooms, And Lentils

small brown or green lentils, rinsed

cold water or chicken stock or broth

extra-virgin olive oil

medium onion, finely chopped

garlic clove, peeled and crushed

unsalted butter

small cremini mushrooms, halved or quartered if large

oyster or other mushrooms, cut into pieces

fine sea salt and freshly ground black pepper

fresh flat-leaf parsley, chopped, plus more for garnish

freshly squeezed lemon juice, plus more to taste

to 12 slices bacon, preferably thick-cut