Zucchini (Cucurbita pepo) is a slender summer squash, harvested young and immature while its skin is still thin and tender and its seeds are barely formed. Mild, faintly green and grassy with a clean cucumber-like coolness, it is more vessel than flavour — soaking up oil, salt and char on the grill, in the pan or under the broiler. Botanically a fruit but eaten as a vegetable, it ranges from the familiar dark-green cylinder to golden, pale and round heirloom forms.