Pre-heat your grill to high heat and lightly grease the grates.
Slather each side of each bread slice with a bit of olive oil and set aside.
Rinse the tomatoes, shake them dry, and set them onto the tin foil. Drizzle a very small bit of olive oil over them and toss to coat. Hit them with some cracked black pepper. (I didn't bother using salt since halloumi is very salty).
Slice the halloumi into 1/4-inch thick pieces width-wise. Then, place your sliced up bread, tomato packet, and halloumi on a large platter to take to the grill. (Hey, bring yourself a drink too ;) )
Place the halloumi directly onto the grill, followed by the tomato packet, and the grilled slices of bread. Depending on space, you may need to grill your bread in batches.
The halloumi and bread slices should only need about 2-3 minutes per side, or until a golden color starts to form. So plan to grill your halloumi and bread slices for 2-3 minutes, then using tongs, carefully flip each slice over and grill for another 2-3 minutes. When done, remove and place on a plate or platter until the tomatoes are done. The tomatoes should only take about 6-8 minutes until the shrivel up and burst. When the tomatoes are done, remove them and bring everything back inside, or to wherever you're preparing your dish.
Drain any excess oil from the tomatoes, then set them in a large bowl. Transfer the halloumi to a cutting board and cut the halloumi into small 1/2-inch cubes. Place the halloumi into the bowl with the tomatoes. Drizzle some of the pesto over the tomatoes and halloumi and give it a good toss. Use as much or as little pesto as you want. When done tossing, top with fresh basil leaves and serve with crusty bread and your favorite wine.