Combine the ground chicken, panko, egg white, garlic, two-thirds of the sliced scallions, soy sauce, ginger, 1/2 teaspoon salt, and pepper in a large bowl. Mix just until combined.

Shape the mixture into about 20 meatballs, keeping them evenly sized so they finish cooking together.

Stir the Greek yogurt, mayonnaise, sweet chili sauce, sriracha, lime juice, and rice vinegar in a small bowl. Shred the cabbage and carrots, dice the cucumber, and set the vegetables aside.

Bring the water and remaining 1/4 teaspoon salt to a boil in a covered saucepan. Stir in the pearl couscous, cover, reduce heat to low, and simmer for 10 minutes. Remove from heat and let stand, covered, for 5 minutes.

Heat the avocado oil in a 12-inch nonstick skillet over medium heat. Brown half the meatballs for 7 to 8 minutes, turning every 2 minutes, then transfer them to a plate.

Cook the remaining meatballs the same way. Return the first batch to the skillet, cover, and cook for 2 to 3 minutes more, until the centers reach 165°F.

Fluff the couscous and divide it among four bowls. Add the cabbage, carrots, cucumber, and meatballs, then drizzle with the sauce.

Finish with the reserved scallions, cilantro, and sesame seeds.