Slice the red peppers into thick slices (I slice one pepper into four pieces typically) and brush with a bit of olive oil.
Place the pepper slices onto a cookie sheet, and roast in the oven for about 20 minutes, flipping once half way through.
While the peppers are roasting take the time to prepare the other veggies. Slice the avocado, wash and dry the lettuce leaves, and slice the tomato.
Heat a large heavy-bottomed pan over medium-high heat. Lightly coat the pan with olive oil, and add the halloumi slices. Fry for 2-4 minutes on each side, until golden brown.
Toast the bread if desired. Spread with mayo, and layer on the roasted red peppers, avocado, tomatoes, lettuce, and halloumi.
Grab a napkin or eat over the sink. This one is drippy!