Using a brush, spread the olive oil on all sides of the halloumi. One teaspoon of olive oil should be enough. Heat a grill pan over medium-high heat. Once the pan is hot, lay all 4 slices of halloumi on the pan. Grill the first side for about 3 minutes, then flip it over and grill the other side for 2 minutes. Remove from heat.
Toast the bread. Mash the avocado, and spread half of the mix on each slice of bread. Sprinkle some dukkah on the avocado if you like.
Layer half of smoked salmon on each slice. Then, layer the sliced cucumber and grilled halloumi on top. Sprinkle pepper flakes if you want some spice.