Slice zucchini, eggplant, and pepper, place the extras inside an air-tight container and put it into the refrigerator. Mix the slices with salt and oil, and cook on a pan. Place them on a plate when they are cooked. Place a slice of halloumi between the vegetable slices. Grill the halloumi with a little oil in a pan, if desired. Pour the pesto sauce over the halloumi and vegetable slices. Repeat the same steps for the extra slices that you put inside the refrigerator, of course, if you are not overwhelmed by the taste of the first plate.