Pre heat a large-sized sauté pan over medium-high heat.  Add 1 tablespoon of oil to the hot pan. Add half of the onion to the pan and  cook for 2 minutes. Add half of the garlic and all the bell peppers to the  onion mixture in the pan. Continue to cook the vegetables in the pan and add  all of the yellow squash and zucchini to the pan.

Lightly season the cooking  vegetables with salt and pepper. Let the vegetables cook until the squash is  just crisp-tender (about two minutes). Remove the vegetables from the pan into  a large serving bowl. Place the sauté pan back over the heat and use a spatula  to remove any debris.

Once the pan is hot again, add 1 tablespoon oil and the  other half of the diced onion. Let the onions cook for 2 minutes and then add  the garlic, mushrooms and eggplant. Lightly season the cooking vegetables with  salt and pepper. Let the vegetables cook until the eggplant is just tender  (about 2 minutes).

Remove the vegetables from the pan and place them into the  bowl with the other vegetables. Add the fresh herbs to the bowl of vegetables  and stir to combine. Serve warm.