Heat the vegetable oil in a large saucepan and cook the garlic, ginger and chilli (reserving a little chilli to serve) for 4-5 mins over a low heat, until fragrant. Turn the heat up slightly, add the chopped tomatoes and cook for another 2 mins.
Slice the spring onions, reserving some of the green parts to serve. Add to the saucepan, followed by the vegetable stock and soy sauce, then season. Bring to the boil and simmer for 5 mins, before blitzing the mixture with a stick blender until it’s almost smooth.
Add the egg noodles to the soup to heat through for 2 mins, then take off the heat and slowly stir in the beaten egg. To serve, divide the soup between 4 bowls, then sprinkle over the remaining spring onion, along with the reserved chilli.