Whisk oyster sauce, pepper, sugar, and fish sauce in a bowl.
Heat oil over medium heat in a medium nonstick skillet and add tofu. Cook 1 minute, stir gently, and add oyster sauce mixture. Cook, stirring occasionally, about 5 minutes, or until tofu is hot and sauce has reduced a little. Garnish with cilantro.
Note: Nutritional analysis is per serving.