Heat a drizzle of oil in a large saucepan, then fry the onion gently for a few minutes until softened. Meanwhile, heat a kettle of water and then blanch the green beans for a few minutes in a small saucepan (if using fresh beans).
Add the curry paste along with a splash of water and stir for a minute or two to release the flavours.
Stir in the coconut milk and crumble in the stock cube, stir around then add the blanched green beans (or frozen green beans) and pepper. Stir around and let it simmer for a few minutes with the lid on the saucepan.
Lay the fish on top of the sauce and vegetables, then replace the lid and simmer for another 8 to 10 minutes or until the fish is just cooked.
Meanwhile, lightly toast the almonds in a dry frying pan (you could get your other add-ons ready during this time, too - rice, coriander, yoghurt, naan, lime/lemon etc.) Serve out the curry into bowls carefully (to keep the fish in large pieces), sprinkle on the coriander and almonds and add a lemon/lime wedge (if using). Enjoy with the yoghurt and your rice and/or naan and/or popadoms as you prefer.
I have successfully used many different types of curry paste in this recipe. It doesn't really matter, although Madras and Korma pastes go well with the creamy coconut milk. For a medium spiced curry, use about 2 tablespoons of curry paste. Use a little more or less to taste.
It's very easy to replace the vegetables with whichever you have. Don't have green beans? Use asparagus, broccoli, mushrooms, zucchini/courgettes, eggplant/aubergine, or any other vegetables that cook fairly quickly.
Can you freeze this fish curry?
I wouldn't recommend it as the fish will overcook when you reheat it. It's best to eat it all in one go.