Meanwhile, finely chop or crush about four to six cloves of garlic with a little ground fennel and pepper, and a generous pinch of salt. Squeeze over the juice of a lemon (and the zest if you like), mix well, and leave for at least half an hour to let the acidity “cook” out the garlic.
Cut a large cucumber lengthways, taking the “cheeks” off the cucumber – the idea here is to remove the seed core, so you’ll need to make a lengthyways cut starting about a third of the way across the width, then do a quarter rotate, repeat, and then another quarter rotate, repeat and one more cut. This will give you four long pieces of cucumber with little or no seeds, each piece narrower than the last. Cut all the pieces, again lengthways, to make a series of roughly 1cm wide strips, and then line these up in groups and cut across. (If you prefer not to eat the skin, remove this before the first step).
When the yoghurt is finished straining – the dripping should have pretty much stopped – mix all three components together well, season to taste, and enjoy!