Combine the peanut oil and garlic in a small bowl. Cut th e tenderloin from th ebottom of each chicken breast half, in one piece if possible. Cut each breast lengthwise into five 1/2-inch-thick strips. (when serving the skewers as a passed finger food without a knife and fork, cut the five !/2 inch thick strips in half horizontally, creating more magageable pieces).
Add the chicken stips and the tenderloins to th egarlic oil, stir until th eoil is evenly distributed, and cover with plastic wrap. Let marinate for 30 minutes and up to 24 hours. Refrigerate if marinating for more than 30 minutes.
Soak the skewers in water for at least 30 minutes to prevent splintering and burning.
Prepare a medium-hot charcoal fire, or preheat a gas grill to medium-high. Oil the grill rack.
Thread 1 piece of chicken onto each skewer, bunching the meat tightly at the end of the skewer. Season with kosher salt and pepper to taste. Grill the chicken until cooked through, about 3 minutes per side.
Divide the cabbage among 4 plates. Arrange 3 skewers on each plate along with a small ramekin of peanut sauce. Sprinkle the chicken with the chopped cilantro and red pepper flakes. Garnish with cilantro sprigs.
Do Ahead: The peanut sauce can be made up to 3 days in advance. Refrigerate until ready to use. Marinate the chicken and skewer the strips up to 1 day in advance. The chicken can be grilled 8 hours in advanced and refrigerated. Be careful not to overcook the meat. Just before serving, cover the skewered chciken with aluminum foil and reheat in a 350F oven for about 5 minutes.