In a large pan or wok, saute sweetpotatoes and rosemary in olive oil over medium high heat, about 5 minutes.
Add peppers and saute a few more minutes. Salt and pepper to taste. Add fennel, red onion and garlic and saute until soft. Reduce heat to medium and add yellow squash and zucchini cooking for about 4 minutes.
Mix in thyme, and orange zest; add tomatoes and balsamic vinegar. Cook 5 more minutes to combine flavors. Remove from heat. Discard rosemary sprig before serving. Garnish with fresh rosemary or thyme.