Soak the noodles according to packet instructions. This should take about 3 minutes, in which time you can prep the pak choi, chilli and spring onion.
Add the soy sauce, fish sauce and spring onion to the bottom of your jar. Drain and rinse the noodles and add to the jar. Layer with the pak choi, spring onion and red chilli, then top with the miso paste, prawns and a wedge of lime.
Once you’re at work, remove the lime wedge and add enough hot water to cover. Stir through until the miso paste has dissolved and all is combined. Squeeze in your lime and enjoy.