Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and dice the sweet potato into small half-inch cubes. Toss them on one side of the baking sheet with 0.5 tsp of olive oil and a pinch of sea salt.
Roast the sweet potatoes for 12 minutes to give them a head start.
While potatoes roast, season the salmon fillet and chicken breast with the remaining olive oil, dried oregano, sea salt, and black pepper.
Remove the tray from the oven. Move the potatoes to one side and add the chicken, salmon, black beans, and corn to the other side of the tray.
Return the tray to the oven and roast for another 12-15 minutes until the chicken reaches an internal temperature of 165°F and the salmon flakes easily with a fork.
Place the fresh spinach in a serving bowl. Top with the roasted sweet potato, black beans, and corn mixture.
Slice the roasted chicken and place it alongside the salmon on top of the greens.
Garnish with sliced fresh cucumbers and a bright squeeze of lemon juice before serving.