In a bowl, whisk together olive oil, lemon zest, lemon juice, honey, garlic powder, oregano, salt, black pepper, and red pepper flakes.
Pound the chicken breasts to an even thickness. Place the chicken in a Ziploc bag and pour in the marinade. Refrigerate for at least 30 minutes.
Heat a grill pan or skillet over medium-high heat. Cook the chicken for about 7 minutes per side until the internal temperature reaches 165°F.
Transfer chicken to a plate and let it rest for 5 minutes before slicing.
In each serving bowl, layer rice, grape tomatoes, chopped cucumber, shredded romaine, and sliced red onion.
To make the tzatziki, mix Greek yogurt, grated cucumber, minced garlic, lemon juice, olive oil, chopped dill, salt, and pepper.
Top the bowls with sliced chicken and a drizzle of homemade tzatziki sauce. Garnish with crumbled feta cheese.