I've been making a very nutritious vegan lentil soup for weeks now. I deliberately make it thin enough to drink from large mugs. A big dose of that plus a couple of tangerines/clems/whatever you want to call them equals lunch.

So for a big batch that will easily give us three big mugs each, this is how I proceed:

Get a vegetable stock pot going. You need two litres for my size batch but it doesn't need to be very strong. I won't buy stock powder or cubes as I have never found any that are not utterly disgusting. In the pot go carrots, carrot peelings, those coarse sticks from the outside of the celery that you don't want to eat, onion peelings and maybe one whole onion, fresh thyme, a bay leaf and a few peppercorns. That gets boiled for about an hour.

The soup ingredients are 220g dried lentils (I use small brown ones that are very cheap. I don't think I'd use red lentils for this, and definitely not split peas), 200g of fresh baby leaf spinach, two carrots, two sticks of celery and an equal amount of shallots or onions, and a big glug of extra virgin olive oil.

Chop up the onions, carrots and celery and fry them gently in the olive oil for about half an hour while the stock is simmering. Wash the lentils and throw them in. Stir them around for a minute, then ladle in the sieved stock, up to around two litres. Don't sweat the amounts. Simmer that for at least half an hour.

When the lentils are soft, throw in the spinach. It reduces down miraculously in no time at all. Let that simmer for five minutes, put the pan in the sink and whizz it with a hand blender. It needs to be well seasoned, a bit at a time, to taste.

The golden rule is not to eat it until tomorrow. You can reheat the whole lot every day until you've finished it. It doesn't hurt it.   Very simple, very tasty, very cheap and really good for you.