Put 2 to 3 tablespoons of the oil into a good-sized saucepan (and one that has a lid that fits) on the heat and when it's warm, add the chopped onion. Sprinkle with salt (which helps prevent its browning) and cook over low to medium heat until soft (about 5 minutes). Add the lentils, stir well and then cover generously with cold water. Bring to the boil, then cover and let simmer gently for 1/2 an hour or so until cooked and most, if not all, the liquid's absorbed. I don't add salt at this stage since the sauce provided by the sausages later (and which will be poured over the lentils) will be pretty salty itself. So, wait and taste. And remember, you can of course cook the lentils in advance.
Anyway, when either the lentils are nearly ready or you're about to reheat them, put a heavy-based frying pan on the burner, cover with a film of oil and add the bruised garlic. Cook for a few minutes then add and brown the sausages. When the sausages are brown on both sides - which won't take more than 5 minutes or so - throw in the wine and water and let bubble up. Cover the pan, either with a lid or aluminum foil, and cook for about 15 minutes. Using a fork, mash the now-soft garlic into the sauce and taste for seasoning, adding a little more water if it's too strong.
Remove the lentils to a shallowish bowl or dish (I evacuate the sausages from their cooking pan, plonk the lentils in, then proceed) then cover with the sausages and their garlicky, winey gravy. Sprinkle over some flat-leaf parsley.