Add the extra virgin olive oil, red wine vinegar, Dijon mustard, dried onion, honey, salt, garlic, oregano, and black pepper to a jar with a tight-fitting lid. Shake vigorously until well combined.
Place the chicken breasts in a resealable food-safe bag or shallow container. Pour in 1/3 cup of the Greek dressing and season with a little additional salt and pepper. Coat the chicken thoroughly.
Refrigerate and marinate for at least 30 minutes or for several hours for deeper flavor.
Preheat an outdoor grill or grill pan over high heat. Once hot, reduce the heat slightly to medium-high.
Remove the chicken from the marinade and discard the marinade that has touched the raw chicken. Grill until browned with visible char marks, then flip and continue cooking until the thickest part reaches an internal temperature of 165°F (74°C).
Transfer the chicken to a clean plate and allow it to rest for about 10 minutes before slicing.
Meanwhile, heat a drizzle of extra virgin olive oil in a large skillet over medium-high heat. Add the frozen cauliflower rice and season with garlic salt, black pepper, and oregano.
Sauté for about 5 minutes, or until the cauliflower rice is tender and excess moisture has evaporated. Finish with a squeeze of fresh lemon juice.
Divide the cauliflower rice among four bowls. Top each Low Carb Greek Chicken Bowl with sliced grilled chicken, cucumber, red onion, tomatoes, Kalamata olives, feta, tzatziki, and fresh herbs.
Finish with reserved Greek dressing that has not come into contact with raw chicken, then serve.
Notes
You can customize this cauliflower rice bowl with additional low-carb vegetables such as bell peppers, lettuce, spinach, or zucchini.