I'm not sure what it means. Is it portions / week, and if so what is a portion. Or 30 different plants.If you have a diverse, balanced diet, aiming to eat 30 plants and vegetables a week – not a problem.
It set me trying to count. I tend to eat the same things each week.
Bread (wholemeal, granary, or seeded) - wheat (the small print on the seeded bread bag adds barley flour, about 5 seeds and vegetable oil)
Potato,
Peas, sweet corn, carrots, sometimes baked beans (in tomato sauce) or tinned tomato or a little celery
Apple, plum, pear, blackcurrants, gooseberries (all home-grown and stored or frozen). And I've just picked a couple of sticks of rhubarb for tonight.
There is a lettuce in the fridge, to go with my bread & cheese lunches, usually in summer I eat salad (lettuce, cucumber, tomato, celery) but in autumn an apple, and when the eaters go soggy, some stewed fruit.
So that's 10 that I eat lots of + maybe 8-10 others.
How can I get up to 30? Well....sugar comes from a plant, and cocoa beans (I'm sure my chocolate biscuits are full of plants). But apart from very occasional and seasonal fruits I'm not sure I can get any further.
So just for fun - how many plants do you eat?