Bring 1L (4 cups) water to the boil in a medium saucepan for the noodles. Thickly slice the pak choy stems, leaving the leaves whole. Pick the coriander leaves, discarding the stems. Halve the tofu pieces on an angle.
Step 2 — Warm tofu
Heat a drizzle of vegetable oil in a medium frypan over medium heat. Cook the tofu for 2 mins each side or until golden and warmed through. Remove from the pan and reserve the pan.
Step 3 — Cook noodles and pak choy
While the tofu is cooking, add the noodles to the pan of boiling water and cook for 5 mins. Add the pak choy, pho seasoning and 1 tsp soy sauce and cook for a further 2 mins or until the noodles and pak choy are tender. Remove the pan from the heat. Taste, then season with salt and pepper.
Step 4 — Cook prawns
Meanwhile, heat a drizzle of vegetable oil in the reserved pan over high heat. Cook the prawns, stirring, for 2-3 mins until just cooked through. Remove the pan from the heat.
Step 5 — Serve up
Divide the noodles, pak choy and soup among bowls. Top with the tofu, prawns, coriander leaves and fried shallots and enjoy!
Step 6 — Make it spicy
Chilli lovers, go wild and scatter over chopped bird's eye chilli to serve.