Preheat your oven to 400°F and line a small baking sheet with parchment paper.
Dice the potato into half-inch cubes and toss them in a bowl with 0.25 tablespoons of olive oil, a pinch of sea salt, and a pinch of black pepper.
Spread the potatoes evenly on the baking sheet and roast for 20 to 25 minutes, flipping halfway through, until they are golden and crispy.
While the potatoes roast, season the chicken breast on both sides with the garlic powder, dried oregano, and the remaining sea salt and black pepper.
Heat the remaining 0.25 tablespoons of olive oil in a medium skillet over medium-high heat.
Place the chicken in the hot pan and sear for 5 to 7 minutes per side, or until the internal temperature reaches 165°F and the exterior is nicely browned.
Remove the chicken from the pan and let it rest for 3 minutes before slicing.
Arrange the fresh baby spinach on a plate and top with the roasted potatoes, sliced chicken, and fresh avocado slices to serve.