In a large mixing bowl, combine coconut milk, curry powder, minced garlic, grated ginger, salt, and sugar to create a flavorful marinade. Add the chicken thighs, ensuring they are fully coated. Cover the bowl with plastic wrap and refrigerate for at least 1 hour.

In a shallow dish, mix rice flour or cornstarch with a pinch of salt and pepper. Dredge each piece of chicken in the mixture once marinating is complete, ensuring they are evenly coated.

Heat oil in a skillet to 350°F (175°C). Fry the coated chicken thighs for about 5-7 minutes on each side until golden brown and internal temperature reaches 165°F (74°C).

Mix together Thai chili sauce and plain yogurt or mayonnaise in a small bowl. Adjust ratio for heat and creaminess, blending until smooth.

Toast buns until golden brown, spread sauce on bottom half, add fried chicken, cucumber, and pickled carrots. Top with fresh herbs and finish with the other half of the bun.

Garnish with fresh cilantro and a sprinkle of lime juice immediately before serving.