In a medium bowl, whisk together 1/3 cup olive oil, sun-dried tomatoes, olives, and thyme. Season with salt and pepper, to taste.
In a medium skillet, heat remaining 3 tablespoons of oil over medium-high heat. Add the shallots and cook until translucent and tender, about 2 to 3 minutes. Add the zucchini, yellow squash, red bell pepper, and 1/2 teaspoon salt. Cook, stirring frequently, for 6 to 8 minutes until the vegetables are tender. Add the warm vegetables to the oil mixture and toss until coated.
Transfer the vegetables to a serving bowl. Serve immediately.