1. Start by making the sauce. Spoon the ketchup, tamari, vinegar, sugar and water into a bowl. Stir together till the sugar has dissolved. Set aside.
2. Cook your noodles. Fill and boil your kettle. If you’re using Thai rice or brown rice noodles, then pop them in a large dish or bowl and pour over enough hot water from the kettle to cover them. Leave them to soak for 6-10 mins. Check them after 6 mins by biting into one. If it's still chalky, leave the noodles to soak for another 2 mins, then check again. Keep checking till they're tender all the way through but still a bit springy. Drain and set aside.
3. If you’re using Asia or udon noodles, fill a large pan with hot water and bring back to the boil. Add the noodles and cook them according to the packet instructions. Drain and toss with the sesame oil.
4. While the noodles are cooking, prepare your protein if you need to. If you have something like whole chicken breasts, pork escalopes, minute steaks or tofu, chop it into small chunks if it’s chicken or tofu, or thin strips if its pork escalopes or minute steaks. Tip them into a bowl and set aside. Wash your board if you had to use it.
5. Prepare your veg. Peel and thinly slice onions. Halve peppers, scoop out the seeds and thinly slice them. Chop broccoli into small, bite-size florets and chop the stalk to match, discarding the dry end. Trim any woody ends off asparagus stems then chop the tender tips into bite-size pieces. Trim courgettes and chop them into rounds. Trim and peel carrots, then chop them into rounds or thin batons. Finely slice any leafy green veg, such as kale or rainbow chard. Set the leafy green veg aside and keep it separate from the other veg.
6. Make your Anything Noodles! Warm 1-2 tbsp oil in a wok or deep frying pan over a high heat. When the wok is hot, add the protein and stir fry till pale brown all over – around 2-4 mins, depending on how thick the pieces are. Scoop them out of the pan and into a clean bowl.
7. Add the veg you’re using, apart from any tender leafy greens, along with around 4 tbsp water if the veg look like they will stick. Stir fry for 3-4 mins till just starting to soften but not too browned or soft.
8. Tip the protein back into the wok. Add any leafy greens and stir to mix, then pour in the stir-fry sauce. Turn the heat down a little and bubble for 1-2 mins till the sauce thickens.
9. Add the cooked and drained noodles to the wok and toss to mix with the veg, protein and sauce. Divide between warm bowls or plates and serve.