Question: how much grams is 1 whole onion?
Answer: We are not aware of any standard sizes or charts for produce, but from Nigella's previous recipes we would consider a large onion to be in the region of 225-275g (8-9 ounces). A medium onion would be smaller than this and around 150-170g (about 6 ounces) and a small onion around 125g (4 1/2 ounces) or below.