Wash and dry all produce. Mince or grate garlic. Halve cucumber lengthwise, then cut crosswise into thin half-moons. Roughly chop cilantro. Zest 1 tsp zest from lime, then halve. Thinly slice chili, removing ribs and seeds first for less heat.

In a medium bowl, toss together cucumber, carrots, half the lime zest, half the cilantro, and juice from one lime half. Season with plenty of salt and pepper. Set aside. Place 3/4 cup water, rice, and big pinch of salt in a small pot. Bring to a boil, then cover, lower heat, and reduce to a gentle simmer. Cook until tender, about 15 minutes.

Meanwhile, heat a drizzle of oil in a medium pan over medium-high heat. Pat chicken dry with a paper towel and season with salt and pepper. Add to pan and cook until browned and no longer pink throughout, 2-4 minutes per side. Remove from pan and transfer to a plate to rest.

Heat a drizzle of oil in same pan over medium heat. Add garlic and cook until fragrant, 30 seconds. Reduce heat to low and stir in soy sauce, half the sriracha, 1 TBSP sugar, and juice from remaining lime half. Let simmer, stirring, until thick and syrupy, 30 seconds to 1 minute. Turn off heat.

In a small bowl, combine mayonnaise, remaining sriracha, and enough water to reach a drizzling consistency (start with 1 tsp). Season with salt and pepper.

Fluff rice with a fork, then stir in remaining lime zest and 1 TBSP butter. Season with salt and pepper. Thinly slice chicken. Divide rice between bowls. Top with chicken and salad. Spoon sauce from pan over chicken. Drizzle everything with sriracha mayo. Garnish with remaining cilantro and chili to taste.