Roasting is arguably the healthiest and tastiest way to prepare your veggies.  It preserves their nutrients while concentrating their natural sugars and flavors which makes them particularly yummy to even the pickiest palates.  Roasting also dramatically shrinks them in size (because it removes their water), making it easier to consume more in 1 sitting.  Based on my years of culinary experience cooking regularly for a family of 6, the veggies that best lend themselves to roasting are cauliflower, broccoli, sweet potatoes, carrots, Brussels sprouts, asparagus, onions, and bell peppers.  Simply place your vegetables of choice on a baking sheet or casserole dish, drizzle or mist with extra-virgin olive oil, sprinkle with kosher salt, and roast at 375-400 degrees until lightly browned (about 15-20 minutes).