This recipe is a love letter to frozen mixed vegetables. You know the ones — the confetti-like mélange of corn, carrots, peas and green beans, cut perfectly like little gems. You might dismiss them as unsophisticated or old-fashioned, but that would be a mistake because they have so much to offer. They bring a playful, retro cheer to the table with practically zero effort, winning over even the pickiest eaters with their sweet, mellow flavor and Lite-Brite colors. Their fun vibe and ultimate convenience belie their substance, as they are nutritionally comparable to their fresh, cooked counterparts.