In a bowl, toss the chicken with the oyster sauce and soy sauce and marinate for 10 minutes.
Mash the garlic and chile in a mortar and pestle until finely smashed (or mince with a knife). In a large skillet or wok, heat the oil over medium-high heat.
When the oil is shimmering-hot, add the garlic-chile mixture and cook until fragrant, about 30 seconds. Increase the heat to high, add the chicken, and cook, stirring, until just cooked through, about 4 minutes. Add the basil and cook until wilted, about 1 minute. Serve with the rice.