Pop the skewers in a dish or glass of water and set aside to soak (this will help stop them burning when you grill the souvlaki).
Peel and crush the garlic clove. Finely chop half the oregano leaves. Pop them in a dish with half the pot of yogurt. Add a pinch of salt and pepper. Stir to mix. Add the diced chicken breast and turn to coat. Set aside.
Tip the bulgar wheat into a heatproof bowl. Pour in 150ml boiling water. Add a pinch of salt. Stir, then cover with a plate and set aside to soak for 10 mins.
Chop half the cucumber into small dice (see our tip for the other half). Finely chop the tomatoes. Finely chop the rest of the oregano leaves. Finely grate the zest from the lemon.
Drain the bulgar wheat if you need to. Tip back into the bowl. Add the chopped veg and most of the oregano. Stir in the lemon juice and 1 tbsp olive oil. Taste and add more salt and pepper if you think it needs it. Set aside.
Heat your grill to high. Line the grill pan with foil (if your grill doesn’t have a grill pan, line a baking tray or roasting tin with foil). Drain the skewers.
Thread the chicken onto the skewers. Place on a wire rack in your grill pan or roasting tin and grill for around 15 mins, turning once or twice, till the chicken is browned all over and cooked through. If you pierce the chicken with a knife, the juices should run clear.
Serve the chicken souvlaki with the bulgar salad, the remaining yogurt, garnished with the rest of the chopped oregano.