- Preheat the grill, setting the burners to high.
- Grill the bell peppers until the skin has slightly blackened. Place in a bowl, cover with plastic wrap and let rest for about 15 minutes. Peel, core and cut each pepper into three pieces. Set aside.
- Slide a toothpick in each onion slice (this will allow them to keep their shape while cooking).
- In a bowl, combine the onions, zucchini, eggplant, garlic and olive oil. Season with salt and pepper.
- Grill the vegetables until tender. Cool on a plate.
- In a saucepan, bring the oil, garlic, bay leaves, thyme and pepper to a boil. Simmer over very low heat until the garlic is cooked through, about 15 minutes. Remove from the heat and add the vinegar. Season with salt and stir to combine.
- Place vegetables in jars, alternating colors. Divide and place the garlic, thyme sprigs and bay leaves over the vegetables. Pour the marinade into the hot jars to fully cover the vegetables. Close the jars, let cool then refrigerate.
- Serve the antipasto at room temperature, as a starter along with bocconcini, tomato and prosciutto or with grilled meats or poultry.