The home environment potentially presents a simple means to increase acceptance of sensory properties of vegetables by preparation. This research investigated how preparation can effectively impact upon children’s acceptance for vegetables. Five- and six-year old children (n = 82, balanced for vegetable consumption) tasted and evaluated two Brassica vegetables, broccoli and cauliflower, each prepared in six different ways via variations in cooking method (boiling versus steaming) and cooking time (3 levels, ranging from 2 to 14 min). Children rated samples for liking and a trained descriptive panel assessed the samples’ sensory properties. Across vegetable types, medium cooking times were liked more than short and long cooking times (p < 0.0001), and these samples were medium firm and cohesive, with a balance of green and cooked flavour notes. Boiled samples were less intense in flavour and taste than steamed samples, but overall did not differ in acceptance. Significant interactions were found. Cooking method played a role in acceptance of broccoli but not cauliflower, with medium steamed broccoli liked the most. There was no difference in acceptance between low and high vegetable consumers, although high vegetable consumers were more discriminating in acceptance for cauliflower. In conclusion, children’s acceptance of Brassica vegetables may be altered by preparation. There may be advantage in promoting steaming of Brassica vegetables to children, as they do not object to the flavour, and steaming is nutritionally preferable to boiling. Very short cooking times lead to an undesirable sensory profile and should be avoided. Recommendations are applicable to children regardless of their vegetable intake.