Cut the Rooster potatoes into 2 cm chunks/cubes. Roughly chop the onion, grate the ginger, crush the garlic, and bruise/crush the lemongrass (using the back of a knife).
Heat a large pot with olive oil and fry the potatoes, onion, ginger, garlic, and lemon grass until fragrant.
Add the yellow curry paste, tomato paste, coconut milk, and fish stock. Bring to a simmer.
Add the cauliflower and broccoli florets. Leave to simmer until tender.
Cut the sweet red pepper into diagonal chunks.
Add the red pepper and uncooked prawns. Simmer for 10 more minutes until the vegetables are still firm to the bite and the prawns are cooked through. Garnish with chopped coriander.
