Preheat your oven to 400°F and line a baking sheet with parchment paper for easy cleanup.
Chop the potato into small cubes and toss them on the baking sheet with 1 tsp of olive oil and half of the sea salt and black pepper.
Roast the potatoes for 20 to 25 minutes until they are golden and achieve a satisfyingly crispy exterior.
Season the chicken breast evenly with the remaining sea salt, black pepper, and the dried oregano.
Heat the remaining 1 tsp of olive oil in a skillet over medium heat and sear the chicken for 6 minutes per side until juicy and fully cooked.
While the chicken rests, whisk the lemon juice and minced garlic in a small bowl, then toss in the diced cucumber, halved cherry tomatoes, and minced red onion.
Slice the chicken and serve it alongside the roasted potatoes and the fresh Greek salad, finishing the dish by crumbling the tangy feta over the top.