Dr. McDougall recommends filling half your plate with non-starchy veggies and half with starches, which he calls the 50/50 plate method. So yes, even for breakfast, eat a bowl of steamed veggies with your oatmeal. If you're still hungry and want seconds, serve yourself the same proportions, half of each.
Of course you don't have to eat them separately as pictured! Have quinoa and chickpeas mixed into your salad, a veggie soup made with potatoes, lentils, carrots, onions, and tomato, or a baked potato loaded with roasted cauliflower and bell peppers.