Preheat oven to 200C (180C for fan oven).
Soak the lentils in a bowl of water.
Heat oil in a large pan, add the finely chopped onions and fry them for 5 to 6 minutes.
Add the finely chopped garlic, rosemary, sage and oregano and cook for one minute before stirring in the tomato puree and cooking for another minute.
Add the tin of chopped tomatoes (why not fill the tin with water and add the water to the pan to get as much tomato as you can), season with salt and ground pepper. Then add another 400ml of water (you can use the tomato tin again as a measure) and add the vegetable stock cube.
Drain the lentils, add them to the pan and simmer them for 20 minutes or until they are soft and the liquid is nearly all absorbed.
Cut the aubergine into discs, approximately 5mm thick and lightly grill them until they're light brown in colour using either a grill or BBQ.
Ladle half the sauce from the pan into a medium ovenproof dish and layer half the aubergines over the top and then repeat with the remaining sauce and aubergine.
Slice the cherry vine tomatoes into discs and add them on top of the aubergine. If you wish you can then sprinkle some fresh rosemary leaves on top.
Put the ricotta into a small bowl, stir in the grated cheese and spread evenly over the tomatoes, aubergine toping.
Bake for 20 to 25 minutes or until the topping is golden brown. Unsure the moussaka is piping hot before serving.