We use various different sauces when baking fish. They all evolve and get tweaked over the years. I'm listing a few of them so we don't lose them. They can be used as marinades for a little while before cooking in addition to being dumped on the fish just before cooking. I often reserve some of the sauce to use to baste the fish during the last few minutes of cooking so the sauce doesn't puddle up and get burned.
Honey-Mustard-Soy
I found the original recipe in one of those magazine-ish things that come in the mail and that have articles that are really elaborate advertisements for expensive kitchen remodels, combined with straight-up advertisements from kitchen-remodeling-related businesses.
The original recipe calls for 2 tablespoons soy sauce, 2 tablespoons mustard, and 2 tablespoons maple syrup, to be mixed and poured over 2 salmon filets (I assume roughly 1.5 to 2 lbs fish total?) which are then grilled.
I switched the maple syrup to honey. I use Grey Poupon Country Dijon Mustard because I like using dijon for this rather than hot-dog mustard and that's what I usually have lying around. I use the Japanese-style soy sauces from the grocery store because I think its stronger flavor works well for this -- Kikkoman, for example. And I use honey because I usually have it around, while I rarely have maple syrup as a pantry staple these days.
So... that means my personal version is a 1:1:1 ratio of soy sauce, mustard, and honey.
If you're eating less than a pound of salmon, it works fine to mix 1 tablespoon of each rather than 2 tablespoons. I usually do that, in fact.
I spread it over the salmon and then bake as usual. If I have way more sauce and it starts to puddle up, I reserve the excess sauce and spread it on the salmon during the last 3-5 minutes of baking.
I suspect that this sauce would work for many kinds of fish, not just salmon and steelhead. It might also work pretty well on chicken though I haven't tried that yet.
"As usual" for salmon means anywhere from around 15-20 minutes at 325F to 10-12 minutes at 400-425F. The lower temperature takes longer but is more forgiving if you're worried about over-cooking the fish or burning a sauce.
Teriyaki-ish
The above recipe led to this variation. It has a somewhat Asian-ish flavor. I usually use it on salmon though it might work well for other kinds of fish.
1 tablespoon each of honey and soy sauce, with a bit of sesame oil and some minced ginger (we've been using a tube of ginger puree that a family member found in the grocery store). I don't really measure the sesame oil and ginger, sorry, but the two of them together are roughly 1 tablespoon, or I might even use 1 tablespoon sesame oil and then add a sploot of ginger. Yes, the sesame oil is likely to lose some flavor if the oven is too hot for too long. Make more sauce (with the same ratios) if making more than a pound or so of fish.
Spread/pour it over your fish and bake as usual. Or marinate for a little while and then bake. We usually use this with salmon or steelhead, but it would probably work well for all kinds of fish and maybe chicken.
I often save some sauce back to add to the fish during the last few minutes of cooking.
Adding a bit of minced garlic would only add to the yumminess. Or add a bit of garlic powder to the sauce.
Ideas and Speculations
I wonder how this 1:1:1 concept could be extended. Maybe shift it back towards the soy-honey-orange idea that's already a recipe on this blog? If so, maybe use orange juice or orange juice concentrate for one of the ingredients. Keep the soy sauce, and maybe add a bit of honey or sesame oil. The ginger puree would probably be good. I am going back and forth on whether mustard would work well.
The basic concept seems to be soy sauce (savory/salty), sweet stuff (honey or maple syrup or maybe a fruit juice), and something flavorful that may act as a binder (mustard, sesame oil + ginger). You could probably substitute wine for the soy sauce (probably white or rose) and that alone would be pretty good (wine, honey, mustard). What other ingredients might work as part of a triad? Jam or jelly? Ketchup or barbeque sauce or steak sauce? Horseradish sauce? Olive oil? Pesto? Flavored vinegars? Other fruit juices? Hmmm...
Lemon cream sauce with mustard
This is from something I found online. I posted about it here, but now, as requested, I'll put it on this blog so we can find it more easily.
It is based on this recipe, though a previous version of the website. (When we first round the recipe, I'm pretty sure it was old-style, no blinking bits and random videos and zillions of silly photos before getting to the recipe. And it was on the 'net WAY earlier than the 2019/2020 that the link claims for it. I probably used a version from 2016 or early 2017. The recipe seems to be the same, as does the person who posted it, but the surrounding stuff is a little different.)
This is a good recipe for using up small quantities of cream. As usual, any kind of cream can be used, not just heavy cream.
It works great with tilapia and probably other mild fish. It wasn't as good when we tried it with chicken.
This makes a lot of sauce as it cooks, which is great to mix with grains and starchy things such as rice or wild rice or freekeh or couscous, etc.
The basic recipe/technique:
Melt a half stick of butter (1/4 cup, 4 Tablespoons, 2 oz.) in the microwave. It doesn't have to be all melted, just really soft and close to melting. Add 1/4 cup cream, 1 tablespoon Dijon mustard, some minced garlic (or garlic powder), salt and pepper, and about 1.5 tablespoons of lemon juice. (I usually use 1/2 of a lemon if I'm using fresh lemon juice, even if it ends up being a bit more than 1.5 tablespoons. Canned lemon juice works, too.) Mix it all up.
Put a few tilapia filets (or any kind of mild-flavored fish) in a greased pan. Pour the sauce over the fish. Add some diced scallions or shallots or bits of onion if desired. The amount of fish isn't too important -- anywhere from about a half pound to two pounds, depending on the ratio of fish to sauce you want to generate.
Bake at 390F (give or take a bit) until it's done, about 10-15 minutes depending on how much fish and how thick the filets are.
The sauce can taste fairly sharp depending on how much lemon juice and mustard is added. I usually use Dijon country mustard because I like the strong mustard flavor and the included mustard seeds.
The amounts again:
1/4 cup butter, melted
1/4 cup cream
1 tablespoon Dijon mustard
1.5 tablespoons lemon juice
salt, pepper, and garlic to taste
optional finely-diced onion or shallot or scallions