Preheat your oven to 400°F (200°C). Peel the sweet potato and cut it into 1/2-inch cubes.
On a parchment-lined baking sheet, toss the sweet potato cubes with 0.5 tbsp of olive oil, 0.125 tsp sea salt, and 0.125 tsp black pepper.
Roast the sweet potatoes for 20-25 minutes, tossing halfway through, until they are tender and caramelized on the edges.
While the potatoes roast, season the chicken breast evenly with garlic powder, dried oregano, and the remaining salt and pepper.
Heat a grill pan or cast-iron skillet over medium-high heat. Once hot, grill the chicken for 6-7 minutes per side or until the internal temperature reaches 165°F.
Remove the chicken from the heat and squeeze the fresh lemon juice over it. Let it rest for 5 minutes before slicing.
In a separate skillet, heat the remaining 0.5 tbsp of olive oil over medium heat. Add the minced garlic clove and sauté for 30 seconds until fragrant.
Add the fresh spinach to the skillet and toss constantly until just wilted, which should take about 1-2 minutes.
Plate the sliced grilled chicken alongside the roasted sweet potatoes and the sautéed spinach for a clean and balanced meal.