In a mixing bowl, combine the coconut milk, curry powder, minced garlic, grated ginger, salt, and sugar. Add the chicken thighs, ensuring they are well-coated. Cover and let marinate in the refrigerator for at least 1 hour, preferably overnight.

In a shallow dish, mix rice flour and a pinch of salt. Remove the marinated chicken and let it sit at room temperature for about 10 minutes. Dredge the chicken in the rice flour mixture.

Heat oil in a deep skillet over medium-high heat until it reaches 350°F (175°C). Fry the coated chicken thighs for about 5-7 minutes on each side until golden brown. Drain on a wire rack.

In a small bowl, whisk together the Thai chili sauce and plain yogurt to make the spicy mayo. Adjust heat to taste and set aside.

Toast the brioche or sandwich buns until golden. Spread spicy mayo on both sides, add fried chicken, and top with cucumbers, pickled carrots, and fresh herbs.

Optionally, add a spritz of lime juice or crushed peanuts on top. Serve immediately and enjoy!