In a saucepan, cover the lentils with water and, to give them great flavour, add the bay leaf, garlic cloves, potato and tomato. Bring to the boil and simmer for around 20-25 minutes (topping up with water if necessary) until the lentils are tender but holding their shape (i.e. not mushy). Drain off 90 percent of the water, discard the bay leaf, tomato skin and garlic skin and mash the potato, tomato and garlic into the lentils with a fork. Add the parsley and around 2 tablespoons of vinegar and 4 tablespoons of olive oil. Mix into the lentils and season carefully to taste.
Season the crème fraîche or yoghurt with salt, pepper and just enough lemon juice to give it a twang-the juice of 1 lemon will probably be enough.
Cut the last 2 inches off the asparagus stalks at an angle and discard. Now’s a good time to get your plates out and round your guests up. Get a very large non-stick frying pan (or two medium ones) hot and lay the pancetta or bacon in it with a little drizzle of olive oil. Once golden and crisp, remove to a platter. Add the asparagus and your lightly seasoned scallops to the pan and cook over a high heat until the scallops are golden on both sides. Remove these to the bacon platter too. Finally drizzle in a little more olive oil and lay in your sage leaves. Fry on both sides for 40 seconds or so until crisp and remove to the platter.
Divide your lentils between four plates and place 3 or 4 scallops per person on top. Scatter the bacon over the top of the scallops, with the sage leaves and asparagus sprinkled around the plate. Serve with a good dollop of your lemon crème fraîche.