A brilliant shortcut for lentil soup

I suppose the last person (possibly the first, too) to be excited by a pot of lentils was Esau. So I won´t say that this is exciting news, but, well it´s certainly changed the way I cook lentils, and that´s something.
It´s a trick I read about in the River Family Cookbook, and it couldn´t be simpler; add red lentils to your pot of brown lentil soup. Genius. Why?
Because the red lentils dissintegrate during cooking, which thickens the soup without your having to bring out the blender.
This works with any lentil soup recipe you might use. My usual method is to heat some oil in the pressure cooker and while it heats to chop a stick of celery, an onion, a clove of garlic and a carrot in the food processor. When this has softened slightly I add a cup of brown lentils and a cup of red lentils, a peeled potato, water to cover by about an inch, and a small bay leaf. I cover, bring up to pressure and leave it for ten minutes (some sources say less time but I hate a crunchy lentil).
You can start with bacon before the vegatables go in, or add chorizo or any sausage, but I like my lentils plain.
Once they´re cooked, add salt or stock powder, a dash of sherry, a knob of butter and a squeeze of lemon. Wonderful stuff.