In a large pot fitted with a steamer basket, bring water to a boil and add vegetables successively starting with broccoli and cauliflower
, about 3 minutes, then snow peas
about 3 more minutes, then cherry tomatoes
, until all vegetables are fork tender (a fork can easily be poked through). Transfer vegetables to a large mixing bowl and season with garlic powder and salt and pepper, to taste, and toss with melted butter.