Preheat your oven to 200°C and line a baking tray with parchment paper.
Slice the potatoes into even wedges and toss them with 2.5 ml of the olive oil, a pinch of the sea salt, and a pinch of the black pepper.
Spread the wedges on the tray and roast for 25-30 minutes until they are golden and crispy on the outside.
While the potatoes roast, slice the seitan into thin strips and toss with the dried oregano and the remaining salt and pepper.
Heat the remaining 2.5 ml of olive oil in a non-stick pan over medium-high heat and sauté the seitan until the edges are browned and slightly crunchy.
Prepare the tzatziki by grating 50 g of the cucumber, squeezing out all excess moisture with a clean towel, and stirring it into the Greek yogurt with minced garlic and lemon juice.
Dice the remaining 30 g of cucumber and combine with the halved cherry tomatoes, sliced red onion, and olives to create a fresh Greek salad.
Assemble your bowl by arranging the roasted potato wedges, seitan gyros, and Greek salad side-by-side, then top with a generous dollop of the homemade tzatziki.