Heat up the oven to 175°C (350°F)
Peel the sweet potato and cut in thick slices (should be one slice per burger)
Place a parchment paper on a baking sheet pan, add the potato slices and cover with the oil on bothe sides then the cajun spice on both sides
Bake in the oven for around 45 min
In the last 10 min you can fry the halloumi slices, slice the tomato and prepare the lettuce.
If you have an avocado then slice it also (just note that it is quite slippery and will make it difficult to eat the burger with any grace..)
Place all ingredients between the buns and enjoy!