Lemon Dill Sauce

My roommate and I brought over company after salsa dancing and we were dying to eat some fish: as students, we hadn't had the opportunity often enough. Searched for a recipe for a nice lemon and dill cream sauce, but the Joy of Cooking just didn't provide. So we made this one instead.

Makes about 1 1/2 cups

1/2 medium onion, finely chopped
3 tbsp butter
1 tbsp flour
1 c half-and-half
2 tbsp chopped fresh dill
2 tbsp lemon juice (1/2 lemon)
1 tsp salt

Saute the onion in 1 tbsp of butter until transparent then remove to side dish. Melt 1 tbsp of the remaining butter and mix thoroughly in a small bowl with the flour. Slowly add a few tablespoons of half-and-half until the mixture is runny. Toss the last 1 tbsp of butter into the pan and add the flour mixture and dill. Bring to a medium heat in the pan, adding all of the remaining half-and-half until thickened. Finally, add the lemon juice and salt (to taste) and reduce the heat. The more time you give the sauce to sit in the pan, the richer the flavour of the dill.