3 cloves garlic
1tsp ground coriander
1/2 tsp cumin
1/2 tsp turmeric
1 large potato
1mug (= half pint size or 10 fl oz) red lentils
1 veg stock cube
1tbs tomato puree
1 to 1.5 tsp Marmite
Note that some ingredients - like the coriander, cumin and turmeric, as well as the tomato puree and Marmite - can be added (or not) according to taste.
Fry onions and garlic in a large soup saucepan with a heavy bottom for 5 mins. It must be large enough to take 3 pints of liquid and 3.5 lbs of veg and lentils, etc. It should have a heavy bottom so you don't burn the onions when you are frying them at the beginning.
After a couple of minutes add the coriander, cumin and turmeric (according to taste)
Chop the veg and add them and add all other ingredients and bring to boil. Then simmer approx 20 to 30 mins or until all cooked. (The longer the better for red lentils.)
When the soup is cooked, use a hand-held blender or a potato-masher to get it to the consistency that you want.