Not cutting the vegetables purposefully

While haphazardly chopping vegetables may be acceptable when tossing them into a pan for the stove or oven, it is an absolute no-no when steaming. You must be methodical in your chopping technique. If you're only steaming one type of vegetable, cutting them into the same size pieces ensures they all cook at roughly the same rate and time, according to The Kitchn. You don't want to have to wait for the larger squash slice to catch up to the scrawnier squash piece.

If you're steaming more than one type of vegetable and one takes longer than the other (carrots take slightly longer than broccoli, for example), make sure to cut the longer-to-steam vegetable in both uniform and smaller sizes. The smaller the bite or hunk of vegetable, the faster it steams.