In a medium bowl, combine coconut milk, curry powder, minced garlic, grated ginger, salt, and sugar. Whisk until smooth, then add chicken thighs, ensuring they are fully coated. Cover and refrigerate for at least 1 hour.

On a plate, mix rice flour or cornstarch with a pinch of salt and pepper. Once your chicken has marinated, remove it from the fridge and let it sit for 10 minutes to come to room temperature. Dredge each marinated piece in the seasoned flour mixture.

In a deep skillet or heavy-bottomed pot, heat oil to 350°F (175°C). Carefully place the coated chicken thighs in the hot oil, frying for 5-7 minutes per side or until golden brown and cooked through. Drain on a paper towel-lined plate.

In a small bowl, whisk together the Thai chili sauce and plain yogurt (or mayonnaise) until well combined.

Lightly toast your buns. Spread a generous amount of spicy sauce on both sides of the buns. Layer fried chicken thighs, cucumber slices, and pickled carrots on the bottom bun. Top with the other half of the bun.

To serve, present the assembled sandwiches or lay out individual components for guests to build their own.