Put the sliced zucchini into the zipper bag. Mix the olive oil, lemon juice, white balsamic vinegar, rosemary leaves, thyme leaves, sea salt, and ground black pepper, and pour over the zucchini. Press the air out and seal, then refrigerate for at least 2 hours.

Preheat the grill. Rub the grill grates with oil and lay each slice of zucchini on the grill, reserving the marinade, and cook over medium-high heat, turning after about 2 minutes to 3 minutes. If you have smaller pieces, you can put those in a grill basket. Brush the reserved marinade on the zucchini slices after turning. Transfer finished zucchini to a bowl or platter and drizzle with the reserved marinade, then serve.