First make the broth. Add the tahini, 2 tablespoons of the soy sauce and the gochujang to a large saucepan over a low heat and gradually whisk in the boiling water. Cook gently until smooth and creamy. Season with salt and pepper.
Heat 1 tablespoon of the oil in a large pan over a medium–high heat. Add the mince and cook for 6–8 minutes until browned in places and starting to crisp, then scoop it out with a slotted spoon into a bowl and set aside.
In the same pan, add the remaining oil and the mushrooms and cook over a medium–high heat for 3 minutes, stirring often, until softened and starting to turn golden. Add the spring onions and mangetout and cook for another 2–3 minutes until just tender. Return the meat to the pan and toss through the vegetables with the remaining soy sauce and heat through briefly.
Add the noodles to the pan with the creamy tahini broth, stir to combine with the liquid, then heat through over a medium heat. Transfer the hot noodle broth to serving bowls. Spoon the mince and vegetable mixture on top and serve with lime wedges for squeezing over, the extra spring onions and some sesame seeds.
