How to Make It
Pat the tofu dry with paper towels to remove excess water. Cut into 1-inch cubes.
Heat a large skillet over high heat. Add the oil and after the oil is hot, carefully add the tofu into a single layer (hot oil may splatter). Turning gently and as little as necessary, sear each side for 2-3 minutes, or until at least 2 -3 sides are golden and crisped.
Lower the heat to medium and carefully add the soy sauce, sake (or vermouth) brown sugar, and rice vinegar to the pan with the tofu. Stir in the red onion. Cook for 30 seconds and then remove from heat.
Garnish with cilantro and serve warm or at room temperature.