Thinly slice the Thai shallots and sprinkle with a pinch of salt. Allow them to sit for about 10 minutes to extract moisture. Heat oil in a frying pan over medium heat and fry the shallots until golden brown and crispy, about 3–5 minutes. Remove and drain on paper towels.

In a dry skillet over medium heat, toast cumin seeds, coriander seeds, and black peppercorns for about 2–3 minutes until aromatic. Transfer to mortar and pestle and grind with garlic and coriander roots until fine paste.

In a large bowl, combine ground spice mixture with palm sugar, fish sauce, and salt. Add tempura flour and gradually pour in ice-cold water. Whisk until smooth.

Make two cuts around the bones of the chicken drumsticks. Coat chicken with the marinade and refrigerate for at least 4 hours, preferably overnight.

Heat oil in a deep pot or wok to 350°F to 375°F. Fry marinated chicken in batches for about 8–10 minutes until golden brown. Transfer to a wire rack or paper towels to drain excess oil.