Heat oil in a large pot over medium-high heat. Season chicken with salt and pepper, sear in batches 3 minutes per side until golden. Set aside.
In the same pot, sauté onion 4 minutes until softened.
Add garlic, cook 1 minute.
Add tomatoes, cook 4 minutes until broken down.
Whisk peanut butter into 1/2 cup of the broth until smooth, then stir into the pot along with the remaining broth.
Return chicken to the pot, nestling it into the sauce.
Cover and simmer 20 minutes until the chicken is cooked through and the sauce has thickened.
Season with salt and pepper, top with cilantro, and serve hot.