Cut tofu into slices slightly thicker than half a centimetre. Mop up any excess moisture with paper towels and sprinkle lightly with salt and crushed pepper.
Heat 1 tsp oil in a non-stick frying pan over medium heat and fry half the tofu slices until lightly seared on both sides. Remove onto a plate, heat the remaining teaspoon of oil and fry the remaining tofu slices. Set aside to cool.
Cut each cucumber into half (crosswise) and then into thin slices lengthwise to make 'ribbons'. Cut onion into half lengthwise and then into thin slices.
Place the cooled tofu, cucumber and onion in a mixing bowl. Combine the dressing ingredients together in a small bowl and pour over the salad ingredients in the mixing bowl. Toss gently before serving on a lettuce-lined serving plate or bowl. Eat soon after assembly.