Peel and grate the garlic (or use a garlic press). 

Trim the pak choi, then thinly slice widthways. Trim and halve the green beans.

Zest and halve the lime.

Heat a drizzle of oil in a large saucepan on high heat.

Once hot, add the mushrooms to the pan and fry, stirring occasionally, until browned, 5-6 mins.

Stir the red Thai style paste, Thai style spice mix (add less if you'd prefer things milder) and garlic into the mushrooms. 

Stir-fry for 1 min. 

Pour the coconut milk, soy sauce, sugar and water for the soup (see pantry for both amounts) into the pan. Drain the prawns.

Bring to the boil, then add the prawns, green beans and the pak choi. Simmer until just tender, 5-6 mins. IMPORTANT: Wash hands and utensils after handling raw prawns. Cook so they're opaque in the middle.

Meanwhile, crush the peanuts in the unopened sachet using a rolling pin.

Add the udon noodles to the soup and cook, using a fork to gently separate them, until warmed through, 2-3 mins.

Remove the pan from the heat. Stir in half the lime juice and a pinch of lime zest.

Taste the soup and add more salt, pepper, lime juice and sugar if needed. 

Share the udon noodle soup between your bowls.

Sprinkle over the peanuts.

Cut any remaining lime into wedges for squeezing over.