Heat the oil in a heavy-based frying pan and gently fry the shallots and garlic for 2-3 minutes.
Add the white wine and continue to cook until the volume of the liquid has reduced by three-quarters.
Add the chicken stock and thyme and bring to the boil. Reduce the heat to a simmer, then add the butter, a cube at a time.
Blend the mixture in a food processor until smooth and return to the pan.
Gently poach the hake in the mixture for 15 minutes, or until cooked through. Remove the fish from the pan and set aside.
Add the edamame beans, cooked mussels and lemon juice to the poaching liquor.
To serve, spoon some mash onto serving plates, top with a piece of hake and spoon over the mussel sauce.