I was really curious about this so I started looking through some of my cook books. I would say depending on the vegetable, most of the books call for frozen or canned veggies. The exceptions are carrots, mushrooms (most of the time), asparagus, lettuce (obviously), green peppers, onions and usually potatoes. Almost all beans are canned, corn is either canned or frozen, broccoli is frozen, etc. Weird. I don't cook many things, just a few simple recipes, but I was surprised.