Pickled Cucumber:
Put the sesame seeds in a small pan and toast over a medium heat until golden. Put in a bowl or container with the remaining ingredients, give it a good mix then cover. Chill in the fridge for 30 minutes. Allow to return to room temperature before serving.
Patties:
Put the cumin seeds in a small pan and fry over a medium heat for 1–2 minutes until aromatic. Put in a large bowl with the remaining ingredients. Divide the mixture into four and shape into patties. Place on a plate or oven tray and cover until you’re ready to cook — if longer than half an hour, place in the fridge.
To assemble:
Smear the butter onto the cut side of each bun and fry or grill cut side down for a minute or so until golden brown.