Put the shallots or button onions in a bowl, cover with boiling water and set aside for 5 mins. Cook the potatoes in a pan of boiling water for 7 mins until tender. Drain and pat dry. Put tomato purée, soy sauce, oil, honey, mustard and seasoning in a bowl, then mix well. Toss the tofu in the marinade. Set aside for at least 10 mins.