Sweet and sour veggie skewers are a delicious combination of tangy and sweet flavors. Chop a variety of vegetables such as bell peppers, pineapple chunks, red onions, and zucchini into bite-sized pieces. In a small bowl, whisk together soy sauce, rice vinegar, ketchup, brown sugar, minced garlic, and cornstarch. Toss the vegetables in the sauce until well coated. Thread the vegetables onto skewers and grill over medium-high heat for about 10-15 minutes, turning occasionally, until they are tender and slightly charred. Serve the skewers with steamed rice and garnish with chopped green onions and sesame seeds.