Celeriac- looks like a dirty, rooty ball, but has a lovely nutty flavour. You need to cut off about 1cm all over to remove the dirt and hard coating. The off-white inside can be eaten raw in a salad/coldslaw, baked or mashed instead of potato and has a nutty/mild celery flavour.
Samphire- (Tesco have it)- goes well lightly fried in butter and garlic and goes well with fish/seafood
Cauli- roasted in Indian herbs or mashed like potato
Leeks- baked with bacon, in a gratin (cheesy leeks)
Mash- any root vegetables can be used, or a combination of several. Last night I only had 2 potatoes left, so for the top of our cottage pie, I used a mash of potato, sweet potato, carrot and parsnip. Swede also works. Root veg can also be cut into wedges and baked. Made into potato/sweet potato bake with cream and garlic
Edamame peas- I buy them frozen and use as a replacement for peas, in a stir-fry or in salads
Corn kernals- either frozen of tinned. Add to stir-fry, make into fritters, in salads, cottage pie and chicken/sweet corn soup
Tenderstem broccoli/bok choy/choy sum/Any Chinese greens- steamed lightly then drizzle a sauce of soy sauce/brown sugar/sesame oil and sprinkle with sesame seeds and/or slithered almonds
Left over fried rice, or those packets of savoury rice can be used to stuff large beef tomatoes, peppers, hollowed out courgettes, squash etc