Make the marinade in advance – at least an hour or the day before. Mix all the marinade ingredients together. Place in a Ziploc bag with the meat cubes and mix everything together well. Store in the fridge if you are making it the day before.
Pre-soak wooden skewers in water if you are making these over a fire.
Thread the meat, peppers, onion and mushrooms onto the skewer making sure not to bunch the meat up too much *tip - ensure that the vegetables are not bigger then the meat cubes as this will prevent the meat from making contact with the griddle pan. If you are making on a braai this will not matter.
Brush lightly with olive oil and cook on a griddle pan on the stove, a gas or conventional braai, turning a few times. Cook to preference.
Spritz with lemon juice and season with salt and pepper before serving with the tzatziki.