Mix all the sauce ingredients together in a small bowl and set aside.
Prepare tofu like you normally would.
Cut thicker broccoli stems into half lengthwise and then into even, bite-size pieces. Cut bok choi leaves off and chop the white part into small pieces and julienne the carrot.
Put a large pot of water onto boil and grab a steaming basket. Once the water is boiling, place broccoli in the steaming basket. Steam for 4 minutes, next add in the white part of the bok choi and steam for a further 2 minutes, finally add in bok choi leaves and julienned carrot and steam for 1 minute.
Cook the spaghetti according to the package instructions.
Cut the dark green part off the spring onions and save them for garnish. Halve the rest lengthwise and then chop into 2.5 cm / 1″ pieces.
Heat up a wok or a deep frying pan. Add oil and warm it up gently. Once warm, add chopped spring onions. Allow them to cook gently in the shimmering oil for about 7 minutes. Make sure the heat is low so that the spring onions cook without turning golden.
Toss the cooked spaghetti with the spring onions and oil.
Mix in the sauce, steamed vegetables, and tofu. Stir-fry for 30 seconds, just to warm up.
Divide between 4 bowls, garnish with sliced spring onion tops.