Cut the tomato into quarters and discard the seeds. Finely chop the flesh. Place it in a small saucepan. Peel and grate in the ginger and garlic. Add 1 tbsp each of the sugar and Worcester sauce and 2 tbsp tamari. Add 50ml cold water and place the pan on the hob. Bring to a bubble then simmer on a low heat for 10 mins. Turn off the heat.
Meanwhile, thinly slice the spring onion and set to one side. Place a large pan of water on to boil.
Halve the pepper and scoop out the seeds and pith. Chop it into small pieces. Trim the dry end from the broccoli. Cut the stalk from the head of the broccoli. Slice the stalk into matchsticks. Chop the broccoli head into small florets. Peel and thinly slice the onion.
Set a frying pan or wok over a medium-high heat. Tip in the sesame seeds and toast them for 2-3 mins till golden and nutty smelling. Transfer to a small bowl.
Add 1 tbsp oil to the hot pan. Place all the prepped veg in and cook for 5 mins, stirring often.
When the veg has gone into the pan, drop the buckwheat noodles into the boiling water. After 1 min, separate them with a fork. Cook for a further 3 mins till tender. Drain and rinse under cold water. Shake dry and place back in the pan.
Add half of the sauce to the noodles and the other half to the veg. Stir each together to coat.
Tip the noodles into the wok with the veg and stir for 2 mins to heat the noodles. Sprinkle in half of the sesame seeds and toss together.
Lift the noodles and veg out on to 2 warm plates. Scatter over the remaining sesame seeds and the sliced spring onion. Add a splash more tamari if, you like, to taste.