Preheat oven to 425°F (218°C). Prepare three seasoning mixes in separate bowls: Mediterranean (oregano, 1 tsp garlic powder, lemon zest), Tex-Mex (cumin, chili powder, paprika), and Asian-inspired (soy sauce, ginger, 1 tsp garlic powder).
Rinse rice until water runs clear. Combine with 4 cups water and ¼ tsp salt in saucepan. Bring to boil, reduce to simmer, cover and cook 40 minutes. Remove from heat, let stand 10 minutes, then fluff.
Divide chicken thighs into three equal portions. Place each portion in separate mixing bowls with one seasoning variation. Add 1 tbsp oil divided between bowls. Massage seasonings into chicken thoroughly.
Line sheet pan with parchment paper or foil. Arrange first batch of chicken in single layer and bake at 425°F for 20-25 minutes until internal temperature reaches 165°F (74°C). Remove, rest 5 minutes, then slice. Repeat with remaining batches.
Heat large skillet over medium-high heat. Add 1 tbsp oil and diced onion. Sauté 3-4 minutes until translucent. Add minced garlic, cook 30 seconds. Add frozen vegetables, cook 5-6 minutes until heated through. Season with salt and pepper.
Slice chicken against the grain into ½-inch strips. Distribute rice evenly among 10 containers (approximately ⅔ cup per container). Add chicken to each container (4-5oz per container). Add vegetable mixture (approximately ¾ cup per container).
Allow to cool completely before securing lids. Refrigerate for up to 5 days or freeze for longer storage.