Marinate the chicken: Whisk marinade ingredients together. Add chicken thighs (open them up so they coat well). Cover or seal and refrigerate 30 minutes to overnight.
Cook the rice: While the chicken marinates, cook rice according to package instructions. Keep warm.
Make the cucumber salad: Combine salad vegetables in a bowl. Whisk dressing ingredients, pour over, and toss. Set aside.
Make the sriracha mayo: Whisk all ingredients together until smooth. Refrigerate until ready to use.
Cook the chicken: Grill over a preheated grill ~5 minutes per side, cooking to 165°F (74°C). Rest briefly, then slice.
Assemble: Divide rice into bowls. Top with sliced chicken, cucumber salad, and a drizzle of sriracha mayo.