For the butterbeans, drain and rinse the pre-soaked beans and place in a deep saucepan, cover with fresh cold water then add the garlic and thyme and bring to a gentle simmer.
Cook gently for approximately 40 minutes, skimming off any scum that rises to the top of the pan, until the beans are just tender, then drain and set aside. Alternatively use canned cooked butter beans that have been drained and rinsed well.
Heat a large non-stick frying pan over a medium heat, add a splash of oil and sauté the diced red onion, chilli, ginger and garlic for one minute. Add the pre-cooked butterbeans (or tinned butterbeans) and lemon zest and cook for a further minute.
Add the chicken stock, increase the heat and simmer for a minute, then remove from the heat.
Add the mint, crème fraîche and half of the chopped dill. Mix well and season to taste with salt and freshly ground black pepper.
For the fish, prepare the plaice fillets. Using a sharp flexible knife trim the plaice of any skin and outer skirt pieces so you have three neat equally sized pieces of plaice per person.
Season the fillets with salt and black pepper.
Heat a large non-stick frying pan over a medium heat. Add a splash of oil then lay the fillets in the pan, presentation side down (which is the flesh side) and cook for two minutes.
Using a fish slice, turn the fillets over and cook for a further minute.
Turn off the heat, squeeze over a little lemon juice, then remove and drain onto kitchen paper.
To serve, arrange the butter beans and sauce in warm serving bowls and lay over the seared plaice. Scatter over the remaining dill and a drizzle of extra virgin olive oil.