Heat the Grill Pan, add the tofu cubes and cook on medium heat, turning sides gently, till evenly browned on both sides. Heat oil in a non stick pan, add spring onions, celery, garlic, ginger, salt and toss.
Add green chillies, crushed black peppercorns and mix. Blend the cornflour in quarter cup of water and add. Mix and add lemon juice. Mix again. Add the grilled tofu and toss gently. Serve hot.