Season the minced beef with salt, pepper and form into two larger patties. Slice both the cucumber and onion into very fine slices. Toast the brioche buns cut-side down in a pan with some butter, place to one side. Fry the patties on both sides in oil for around 2–3 minutes and then spread with the Obazda. Cover the bottom half of the buns with the cucumber slices and salad leaves, add the patties on top, then place the onions and cress on top, and top with the other half of the bun, securing with a skewer if required.