Preheat your oven to 400°F and line a small baking sheet with parchment paper.
Peel the beets and dice them into 1/2-inch cubes, then toss with 1 tsp of olive oil and a pinch of sea salt.
Spread the beets on the baking sheet and roast for 25 minutes until tender when pierced with a fork.
Season the chicken breast with sea salt, black pepper, and dried oregano.
Heat a grill pan or skillet over medium-high heat and cook the chicken for 6-7 minutes per side until the internal temperature reaches 165°F.
Remove the chicken from the heat and let it rest for 5 minutes before slicing into thin strips.
Dice the green bell pepper, cucumber, and red onion, and slice the cherry tomatoes in half.
In a small jar or bowl, whisk together the remaining 1 tsp of olive oil and the lemon juice to create the dressing.
Place the spring mix in a large bowl, drizzle with the dressing, and toss gently to coat.
Top the greens with the roasted beets, chopped vegetables, sliced chicken, and crumbled feta cheese.