In a bowl, combine soy sauce, brown sugar, vegetable oil, curry powder, ground coriander, ground cumin, minced garlic, minced ginger, and tamarind paste (if using).
Add the chicken pieces to the marinade, ensuring they are well coated. Cover and refrigerate for at least 1 hour, or overnight for best results.
In a saucepan, combine peanut butter, coconut milk, soy sauce, brown sugar, lime juice, and chili sauce.
Heat over medium heat, stirring constantly until the sauce is smooth and well combined. Add water gradually until you reach the desired consistency. Keep warm.
Preheat a grill or grill pan to medium-high heat.
Thread the marinated chicken pieces onto skewers.
Grill the chicken skewers for about 3-4 minutes per side, or until fully cooked and slightly charred.
Arrange the grilled chicken satay on a serving plate.
Enjoy your meal!