Wash and dry all produce. Mince or grate garlic. Trim and halve cucumber lengthwise; thinly slice crosswise into half-moons. Roughly chop cilantro. Zest and halve lime (for 4 servings, zest 1 lime and halve both). Thinly slice chili.

In a medium bowl, combine cucumber, carrots, half the lime zest, half the cilantro, and juice from half the lime. Season with plenty of salt and pepper; set aside. In a small pot, combine rice, ¾ cup water (1½ cups for 4 servings), and a big pinch of salt. Bring to a boil, then cover and reduce to a low simmer. Cook until rice is tender, 15-18 minutes. Keep covered off heat until ready to serve.

While rice cooks, pat chicken dry with paper towels and season with salt and pepper. Heat a drizzle of oil in a large pan over medium-high heat. Add chicken and cook until browned and cooked through, 3-5 minutes per side. Transfer to a cutting board 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 ponzu, 1 TBSP sugar (1½ TBSP for 4 servings), and sriracha to taste (save some for the next step). Simmer, stirring, until thickened and syrupy, 2-3 minutes. Turn off heat.

In a small bowl, combine mayonnaise and remaining sriracha to taste. Add water 1 tsp at a time until mixture reaches a drizzling consistency. Season with salt and pepper.

Fluff rice with a fork; stir in remaining lime zest and 1 TBSP butter (2 TBSP for 4 servings) and season with salt and pepper. Divide between bowls. Thinly slice chicken. Top rice with chicken and salad. Drizzle chicken with sauce. Garnish with sriracha mayo, remaining cilantro, and chili to taste. Cut remaining lime into wedges and serve on the side.