Start this recipe by frying the onion and garlic together in a pan with a drop of oil for 3-4 minutes to soften. Place the beef mince in a medium sized bowl and add the onion and garlic. Add the beef seasoning and fresh thyme and season well with pepper and salt. Mix all the ingredients together well and divide into 4 balls. Cut the cheese into 4 pieces and stuff a piece into each ball of mince. Roll again into a small ball and flatten into a burger shape. Heat the remaining oil in a pan and quickly pan-fry the burgers on both sides till cooked through. Cut the bread buns in half and toast lightly. Spread over a little mayonnaise onto each piece. Place some salad leaves on the bottom pieces of the buns and place the cooked burgers on top. Cover with a slice of tomato and place on the top of the bun. Insert a small wooden kebab stick through and serve with crispy potato wedges.