Set aside. For the lime butter sauce, heat the olive oil in a small saucepan, add the onion and fry over a gentle heat until softened but not coloured. Add the white wine and simmer until the ...

Meanwhile, put the shallot (or red onion), garlic and wine into a medium saucepan ... whisking well between each addition to make a thick sauce. Whisk in the lime zest and juice.