Cut the chicken breasts into uniform bite-sized pieces, roughly 1-inch cubes. Season generously with salt and pepper.

Heat the vegetable oil in a large skillet over medium-high heat. Once the oil shimmers, add the chicken pieces in a single layer. Cook for 5-7 minutes, stirring occasionally, until the chicken is golden brown on all sides, no longer pink in the center, and reaches an internal temperature of 165°F. Transfer to a plate and set aside.

Lower the heat to medium and add the minced garlic to the same skillet. Sauté for about one minute until fragrant but not browned.

Add the soy sauce, peanut butter, and coconut milk to the skillet. Whisk everything together until the peanut butter fully dissolves and the sauce becomes smooth and creamy, about 2 minutes of constant stirring. The sauce should coat the back of a spoon when ready.

Return the cooked chicken to the skillet, tossing to coat each piece in the sauce. Let everything simmer together for 2-3 minutes so the flavors meld and the sauce thickens slightly.

Serve immediately over rice or noodles. Garnish with chopped peanuts for crunch or fresh cilantro for brightness.