Put the lamb, crushed garlic, mint, chopped olives, tomato puree, salt and freshly ground pepper in a mixing bowl and mix well. Divide into four portions.
In a separate bowl, mix the feta cheese with the thyme. It doesn't matter if it crumbles, just gently squeeze together.
Take a quarter of the mixture into your hand and roll into a ball. Flatten out, put a quarter of the feta in the middle and then draw the meat up around it.
Make sure the cheese is secure within the meat. Repeat with the other three burgers and chill in the fridge for 10 minutes.
In the meantime, make the salad by mixing the cucumber, tomatoes, red onion and olives together in a bowl. Season with salt and freshly ground pepper.
Whisk the olive oil, cider vinegar and honey together and pour over the salad.
Heat a griddle pan until hot. Rub each slice of bread with the garlic clove and sprinkle with olive oil.
Cook the bread on the griddle pan until brown on each sides. Keep warm.
Now cook the burgers on a griddle pan. Turn once after five minutes, then cook for another 5 minutes on the other side.
Spread the mayonnaise on the toasted bread. Top each slice with a freshly griddled lamb burger and a small handful of salad and serve at once.