1 red onion, sliced thinly
1 head fennel, sliced thinly
2 lbs new potatoes, any variety, halved or quartered
1 cup white wine or hard cider
4 tbsp softened butter
1 tbsp capers, roughly chopped
1 clove garlic, minced
1 lemon, zest and juice
2 filet whitefish, each cut into half to make 4 filet