white fish with dill sauce

i have almost zero experience cooking fish, other than making a tuna sandwich!  but we're aiming to eat fish at least once a week, so i'm learning quick.  we tried this last night and it was a very tasty and very easy success!  i served it with corn (frozen) and a wheat berry and broccoli salad (next recipe).
i adapted this recipe to lower the fat and sodium and my changes are in italics.

White Fish with Dill Sauce - serves 4
prep time: 15 mins   cook time: 10-20 minutes
adapted from: healthy quick meals

Preheat oven to 425F/220C

1 tbsp butter, melted - i used salt-free becel margerine
1 lb/500g fish fillets - i used a 650g package of frozen sole fillets (thawed)
1/2 cup sour cream - i used fat free
2 tbsp butter, melted - margerine
2 tbsp minced onion
2 tsp dried dill
1/2 tsp salt - i completely omitted it and didn't miss it!
1/4 tsp thyme
1/4 tsp pepper

Grease a baking dish with the first amount of melted butter.
Place the fish in the baking dish.  since the sole fillets were so thin, i layered them - about 3 fillets thick
Combine the sour cream, melted butter, onion, and spices.  Spread this over the fish.
Bake until the sauce is bubbly and the fish flakes easily with a fork (about 10 minutes per inch of thickness or 5 minutes per cm.)  i think i left it in about 15 minutes total.