Bring a large pot of water to a boil. I use a kettle to speed things up usually. Place about 120 grams of sweet potato glass noodles in the hot water, add a pinch of salt and stir through. There should be enough water to cover the noodles but they won't expand a great deal, so you don't need a full pot. Cook for 6-7 minutes.
Strain the noodles (you can reserve this hot water for the spinach step below), then leave them in some cold water to cool, while you prepare the rest of the ingredients.
Boil a little more water either in a small pot or in a kettle. Add spinach to a pot and cover with boiling water. Cook for 45-60 seconds, stirring around. Strain and cool, then squeeze gently to remove excess liquid. Set aside.
Cut the carrot in halves and then slice into matchsticks or strips. Cut the spring onions (scallions) and sweet red peppers into strips as well. Thinly slice or chop the ginger and chilli and set aside. You can also chop the garlic for the sauce at this stage.
Wash the bok choy well between the leaves and cut in halves. You can leave the firm part of the root. Set aside.
Mix the sauce ingredients in a bowl. Take 3 tablespoons and add to another bowl, which we’ll use as the sauce for the shrimp.
Prepare the prawns. If using frozen prawns, soak them in warm water for 5 minutes and pat dry with a paper towel. If using shelled fresh prawns, deshell and remove the heads. We are now ready to cook our stir fry.
Add a tablespoon of oil to a large frying pan and heat over high heat. Once hot, add the bok choy halves, cut side down. Cook for 1.5-2 minutes until charred, then flip over and cook for another minute. Transfer to a plate.
To the same frying pan, add the onions, carrots, peppers, ginger, chili and another spoonful of oil. Stir-fry over high heat for 1-2 minutes.
Strain and add the noodles to the frying pan together with wilted spinach. Add the sauce, reserving the 3 tablespoons that we saved for the prawns. Stir through and cook over medium-high heat for 2-3 minutes. Keep stirring, allowing the sauce to darken and caramelise slightly. The noodles will also darken as the sauce gets thicker. Have a quick taste and if needed, add a little more Tamari sauce or coconut aminos and sweet syrup (in equal parts, so if you add more salt, make sure the sweetness is balanced). Remove all of the noodles and vegetables to a bowl or a plate.
Add the prawns to the frying pan and bring the heat back to high. Pour over the reserved sauce and cook, stirring frequently, for 2-3 minutes. The sauce will thicken and caramelise, coating the prawns with sticky glaze. Once it's all thick and sticky, add the stir-fried noodles back in and combine. You can also remove the prawns first and serve them on top of noodles. Serve bok choy on top, drizzle with a little extra Tamari sauce or lemon juice and sesame oil.