Combine olive oil, juice, maple syrup, and zest in a small bowl. Whisk ingredients together well, then season to taste with salt and peper. Set aside.
Grill Vegetables and Cheese:
Heat a grill pan over medium heat, OR preheat an outdoor grill to medium-high.
Lightly brush vegetables and cheese with cooking oil.
Grill vegetables and cheese on one side without moving. When grill marks appear, flip and cook on other side. (If you are grilling outside, use a grill basket for the tomatoes, onions, and cheese.)
Remove vegetables and cheese from grill. Season veggies with salt and pepper.
Toss lettuce with just enough of the dressing to coat. Arrange on a platter.
Top lettuce with grilled vegetables. Drizzle veggies with dressing.
Add olives (if using) and halloumi to salad.
Serve immediately. Enjoy!
If you are using a grill pan and cooking indoors, I recommend using an oil with a high smoke point (here's a good list). Doing so will produce less smoke in your kitchen. When cooking on an outdoor grill, I use extra virgin olive oil, although other oils will work, too.