Mix together the oil, herbs, spices and garlic in a large sealable bag. Divide a 250g block of halloumi into 8 slices. It can be very salty, so soak the slices in cold water for at least 10 mins, if you have time. Pat dry, then rub a spoonful of the Cajun mix into each slice, and reserve? 4 slices for Open rye sandwich (see 'goes well with').
In a large bowl, mix all the ingredients for the bean salad. Stir well and set aside.
For the guacamole, scoop the flesh from the avocado and put it in a medium bowl, chopping it roughly with the side of the spoon. Add the rest of the ingredients and mix well. If you prefer your guacamole to be smoother, mash the avocado well with the olive oil and lime juice until it’s at your preferred consistency before stirring in the other ingredients.
Heat the grill. Line a grill pan with foil, place the halloumi slices on it and grill for 3-4 mins, checking occasionally until golden.
Set aside 2 tbsp guacamole for tomorrow’s lunch and chill. Place 2 slices of halloumi on each plate, with some bean salad and a dollop of guacamole on the side.