If you've ever had traditional English fish and chips, there's a chance you'll have noticed 'mushy peas' on the menu.
Mushy peas are marrowfat peas, simmered until they form a thick soup. Ideally you've still got lumps of pea floating in a thick puree. You might add vinegar, or mint sauce, for added flavour.
Mushy peas always used to be incredibly bright green - quite lurid in fact. But this isn't the natural colour - it's all down to a couple of colourings (E102 and E133 if you must know). These are increasingly being phased out, so it's more likely that you'll see mushy peas in future in their natural greyish-green colour; less attractive perhaps, but definitely better for you.
The traditional homeland of the mushy pea is the north of England, particularly Yorkshire. But they've definitely come south now, appearing in chippies all over London. The Golden Hind, Marylebone Lane W1apparently has particularly nice ones - and some modern British cuisine restaurants also seem to have adopted the mushy pea.
Mushy peas might be served on their own, or with a buttered roll. Or you can get mushy peas and chips. Another variation is pie and mushy peas - a small steak and kidney pie with the peas poured all over it. Or, of course, mushy peas as a side order with your cod and chips.
If you want to cook your own, you can try an authentic approach, but something that works just as well is a more foodie version. Take petits pois, and simmer them with a sprig of mint. When they're soft, plunge the peas into cold water to set the colour - otherwise they'll turn rather grey. Then fry a couple of chopped shallots in butter, add the peas with another sprig of mint, then add a little stock, cook for a couple of minutes and blitz in a food processor. Marvellous!
I just love the color and the texture of it well done @fitiliper1985