In a large mixing bowl, combine the chicken cubes, salt, and pepper. Thread about 4-5 chicken cubes onto each bamboo skewers. Set aside.
To make the marinade, combine soy sauce, brown sugar, Indonesian sweet soy sauce, and melted margarine in a large flat-bottomed plate and mix well. Place the chicken skewers in the marinade, making sure both sides are well coated.
Grease pan with oil and heat over medium high heat. Make sure the pan's bottom is large enough in order to be able to lay the chicken skewers flat. Grill the chicken skewers for about 3 minutes on each side or until fully cooked. Remove from heat. Dip the cooked chicken skewers back into the marinade and grill over high heat until charred and browned.
To make the spicy peanut sauce, combine the fresh red chillies, garlic, and red onions in a food processor and blend until smooth. In a mixing bowl, combine the mixture with the smooth peanut butter and warm water until well incorporated. Cook sauce over medium heat for about 5 minutes and add the Indonesian soy sauce, salt, and pepper. If sauce is too thick, add more warm water.
To serve, place cooked chicken satays on a plate and pour spicy peanut sauce over the chickens. Top with some more Indonesian sweet soy sauce and fried shallots.