Step 1: Mix up the mayo, lemon juice, black pepper, garlic powder (or crushed garlic), and hot sauce (optional). Set aside.
Step 2: Pat the halloumi slices dry all around, then brush the onion slices and halloumi with oil. Sprinkle with black pepper.
Step 3: Grill the halloumi, onion rounds, and bread slices on an oiled, pre-heated grill pan. Grill for 2 - 3 minutes per side.
Step 4: Now we can start to assemble the sandwich. Spread the garlic mayo onto both slices of the grilled bread.
Step 5: Next, build the sandwich by layering the grilled halloumi, grilled onions, and lettuce and tomato onto the bread. Enjoy!
RECIPE TIPS: -eat the sandwich right away to enjoy the gooey, creamy texture of the halloumi! -feel free to add more garlic, lemon, or hot sauce to the mayo to suit your tastes.