Spray a wok or large frying pan with low-calorie cooking spray, and set on a medium heat. Add the ginger and garlic and fry for 2-4 minutes until they become aromatic. Add in the soy sauce, fish sauce, rice vinegar, granulated sweetener, tomato puree, lime juice and dried chilli flakes. Add the stock cube to the boiling water and stir until dissolved. Pour into the pan. Increase the heat to high and cook for 10 minutes, stirring often.
While you wait for the sauce to reduce, boil a kettle of water, and pour into a large bowl. Submerge the noodles and set aside. Preheat your oven to 200°C, ready for the salmon.
Tip the reduced sauce into a jug (you’ll use half for the salmon and half for the noodles). Wipe down the frying pan, spray with low-calorie cooking spray and add to a medium heat. When the pan is VERY hot, add the salmon, skin-side down. Leave the salmon alone for 5 minutes – don't shake the pan or touch them, just leave them to sizzle!
Once you start to see the corners of the salmon curl up, it's time to tip in the half of the sauce that you put aside. It will spit and bubble, so be careful! Baste the salmon with some of the sauce and place in the preheated oven for 10 minutes
Now it's time to make the noodles! Drain the noodles off and set them aside to use shortly.
Spray a wok or frying pan with low-calorie cooking spray and set on a medium heat. Add the peppers and spring onion and fry for 5-6 minutes, until softening. Add the mangetout and sugar snap peas, and cook for a further 3-4 minutes.
Add the drained noodles and the rest of the sauce, stirring everything together. Add the pak choi and turn the heat down to a simmer.
Chop up the lime. Slice 3 times (to make 2 slices) and then cut the ends in half to make wedges.
To check on the salmon, lift a flake or 2 in the middle and see if it's cooked. It probably won't be quite ready, so add a lime slice to the top of each fillet. Baste with the sauce and put back in the oven for a further 5 minutes. You'll notice the sauce will have gone nice and sticky...this is what we want!
Check the salmon again; it should be ready to serve. Plate up the noodles first, then top with the salmon and some of the sauce. Garnish with the lime wedges.