Wash and dry all produce. Place chicken in a medium bowl. Pat dry with paper towels and season all over with pepper. Sprinkle all over with cornstarch; toss to evenly coat.

Quarter lime. Peel and halve cucumber lengthwise. Scoop out and discard seeds with a spoon. Slice cucumber crosswise into thin half-moons. Trim and thinly slice scallions, separating whites from greens. In a second medium bowl, combine cucumber, scallion whites, vinegar, half the sesame oil, 1 tsp sugar (2 tsp for 4 servings), and a large pinch of salt and pepper.

In a small pot, combine rice, 3/4 cup water (11/2 cups for 4 servings), and a pinch of salt. Bring to a boil, then cover and reduce to a gentle simmer. Cook until tender, about 15 minutes. Keep covered off heat.

Heat a large drizzle of oil in a large pan over medium-high heat (use a nonstick pan if you have one). Add chicken and cook, stirring, until browned and cooked through, about 5 minutes. While chicken cooks, in a small bowl, combine soy sauce, 2 tsp sesame oil (4 tsp for 4 servings), 4 tsp sugar (8 tsp for 4 servings), and sriracha. TIP: Add the sriracha to taste—use all if you like it spicy or 3 tsp for mild heat.

Once chicken is done, turn off heat and remove from pan. Discard excess oil and let pan cool for about 30 seconds. Add soy sauce mixture to pan and let bubble using residual heat. (TIP: If sauce doesn’t bubble, heat pan over medium-low heat until it does.) Return chicken to pan and toss to coat. Fluff rice with a fork and stir in remaining sesame oil, a squeeze of lime juice, and half the scallion greens. Season with salt and pepper.

Divide rice, chicken, and cucumber salad between bowls. Drizzle with any remaining sauce. Sprinkle with sesame seeds, chili flakes (to taste), and remaining scallion greens. Serve with remaining lime wedges.