In a bowl, mix together coconut milk, curry powder, minced garlic, grated ginger, salt, and sugar until well combined. Submerge chicken thighs in the marinade, ensuring each piece is thoroughly coated. Cover the bowl and refrigerate for at least 1 hour, or ideally overnight.

On a plate, combine rice flour (or cornstarch) with a pinch of salt and pepper. Ensure the ingredients are evenly mixed.

After marination, remove chicken thighs from the marinade and allow any excess to drip off. Dredge each piece in the rice flour mixture until fully coated.

Heat oil in a deep skillet to 350°F (175°C). Add coated chicken thighs and fry for 5-7 minutes on each side until golden brown and cooked through. Drain on a wire rack.

In a small bowl, whisk together Thai chili sauce and plain yogurt until smooth. Adjust the spice level as desired.

Slice cucumbers and prepare pickled carrots. Toast brioche or sandwich buns on a skillet until golden brown.

Spread chili sauce on the insides of the buns. Layer with fried chicken, cucumbers, and pickled carrots. Add fresh herbs or lime if desired.