Preheat your oven to 400°F (200°C).
Dice the red potatoes into small, uniform cubes and toss them with half of the olive oil and a pinch of sea salt.
Spread the potatoes on a parchment-lined baking sheet and roast for 20 minutes.
Slice the zucchini and red bell pepper into bite-sized pieces and toss with the remaining olive oil.
Add the zucchini and peppers to the baking sheet with the potatoes and roast for another 15 minutes until tender and slightly caramelized.
While the vegetables roast, season the chicken breast with dried oregano and pan-sear in a non-stick skillet over medium heat until the internal temperature reaches 165°F.
Let the chicken rest for 5 minutes before dicing it into cubes.
In a small mixing bowl, whisk together the non-fat Greek yogurt and lemon juice to create a smooth, creamy dressing.
Combine the roasted potatoes, mixed vegetables, and diced chicken in a large bowl.
Drizzle the yogurt dressing over the mixture and toss gently to coat before serving.