Peel the potatoes and cut them into wedges. Place in a large bowl and add the olive oil, lemon zest and juice, and season with a generous pinch of salt, dried oregano, garlic powder and a crack of black pepper. Toss to combine.
To air fry: Place in the air fryer basket in a single layer and air fry at 190℃/375℉, giving the basket a good shake halfway through cooking, until the potatoes are fork tender and golden brown and crisp around the edges.
To roast: Preheat the oven to 200℃/400℉. Place the potatoes on a greased baking sheet and roast for 30-40 minutes until golden brown and crisp.
Tear, cut or grate the bread into small pieces and place in a bowl. Pour over the milk and allow to soak.
Add all the meatball ingredients in a large bowl and mix until combined. Form the meatballs into golf-ball sized balls.
To pan fry: Heat a large frying pan over medium-high heat, add a splash of olive oil and cook the meatballs for a minute or two per side until they're just done.
To air fry: Preheat the air fryer to 205℃/400℉. Add the meatballs to the air fryer basket, spray with a little oil and air fry for 12 minutes, shaking half-way through cooking, until just-cooked and golden brown.
To make the tzatziki, grate the cucumber, season with salt and squeeze out as much of the water as possible. Add to a bowl with the Greek yogurt and seasonings. Mix to combine and keep in the fridge until you're ready to serve.
Slice the cucumber, tomatoes and red onion and place in a large bowl. Crumble or cube the feta and add to the bowl. Dress the salad right before serving to prevent the vegetables from going soggy.
Add the potatoes, salad and meatballs to serving bowls. Add a generous dollop of tzatziki and lemon wedges for squeezing. Crumble over a little extra feta cheese and serve.