Grind the coriander seeds, cumin seeds, and peppercorns in a coffee grinder or mortar and pestle until very fine, then transfer to a mixing bowl. Add the brown sugar, salt, turmeric, cinnamon, tamarind paste, and coconut milk; stir to mix well.

Add the chicken to the marinade and mix very well to ensure all the pieces are coated. Marinate at room temperature for 20 minutes or cover and refrigerate for up to 1 day.

Using a mortar and pestle or a food processor, grind the peanuts until mealy. If using a machine, be careful not to turn this into peanut butter; you want texture in the peanut sauce.

Put about ⅓ cup (80 ml) of coconut milk in a small pot and bring to a boil over medium heat. Add the curry paste and cook for about 3 minutes, stirring constantly until the mixture is very thick and the coconut oil starts to separate from the paste.

Add the remaining coconut milk and stir to mix well. Add the peanuts, tamarind paste, and palm sugar, and simmer gently for 5 minutes, stirring frequently, until thickened into a dip consistency.

Taste and add fish sauce as needed. If it tastes a little flat, add a bit more tamarind paste to bump up the acidity.

In a small pot, combine the vinegar, sugar, and salt. Cook over medium heat just until the sugar is completely dissolved. Let cool completely.

Cut the cucumber in half lengthwise, then thinly slice crosswise so you get half-moon pieces. Place the cucumber and chilies in a small serving bowl and pour the cooled vinegar mixture overtop.

To grill: Preheat the grill on high heat, then arrange the chicken perpendicular to the grates, discarding the marinade. Cook with the lid open for 2 to 3 minutes, then flip and cook on the other side for another 2 minutes or until cooked through.

To pan-fry: Place a large nonstick skillet over high heat. Pour in enough oil to thinly coat the bottom. Once the oil is hot, use tongs to lift the chicken strips out of the marinade one piece at a time, shaking off any excess, and place them in the pan.

Serve the chicken with the peanut sauce for dipping, and with the pickles and jasmine rice and/or toast on the side.