1. Put them in the sun: The outer layer of mushrooms is rich in ergosterol, a chemical that’s converted to vitamin D when exposed to sunlight. Put them gill side up on a sunny windowsill for 30 to 60 minutes to turn them into a source of this bone-building vitamin.
2. Stuff them with lentils: Fill Portobello mushrooms with 50g of ready-cooked lentils and sprinkle over a little Parmesan — each one will provide 10g of protein (more than an egg or glass of milk).
3. Boil first: To saute mushrooms with less fat, cover with water, add ½ tbsp of oil or butter per 100g. Boil until the water evaporates then brown in the pan. Wet mushrooms are less porous so won’t absorb so much fat.
4. Add to salads: Raw mushrooms provide more folic acid (needed for healthy blood and in pregnancy). Cooking destroys up to 60 per cent.
5. Serve with a source of vitamin C: Mushrooms supply B vitamins and the mineral selenium, but aren’t a good source of vitamin C. So, serve them alongside broccoli, kale ormangetout.