In a mixing bowl, whisk together coconut milk, curry powder, minced garlic, grated ginger, salt, and sugar until well combined. Add chicken thighs, ensuring they are thoroughly coated in the marinade. Cover the bowl with plastic wrap and let the chicken marinate in the refrigerator for at least 1 hour, or overnight for a deeper flavor infusion.

On a large plate, combine rice flour or cornstarch with a pinch of salt and pepper for seasoning. Once the chicken has marinated, take each thigh and dredge it in the dry mixture, pressing gently to ensure an even coating.

Heat vegetable oil in a deep skillet over medium-high heat until it reaches 350°F (175°C). Carefully add the coated chicken, frying for about 5-7 minutes on each side until they turn golden brown and have an internal temperature of 165°F (74°C). Transfer the chicken to a wire rack or paper towels to drain excess oil.

In a separate bowl, whisk together the Thai chili sauce and plain yogurt (or mayonnaise) until smooth and creamy.

Toast your buns lightly for added texture and flavor. Spread a generous layer of the creamy Thai chili sauce on both halves of each bun. Layer with the crispy fried chicken, followed by sliced cucumbers, pickled carrots, and a sprinkle of fresh herbs.

For an extra burst of flavor, consider garnishing your sandwich with a few cilantro sprigs, a squeeze of fresh lime juice, or a scattering of crushed peanuts.