Eggs – What’s the best method for preparing a smoked cod roe breakfast

Great french toast starts with the bread. You're looking for two things: thick slices, and staleness. Why stale? Stale bread has enough firmness to stand up to the custard. If you don't have stale bread available, you can set it out the night before in a simple wire rack. At least 8 hours should be enough to stale it up nicely. They will be rather firm to the touch.

The ideal finished product is crispy on the outside and creamy in the middle. This might be what you mean by mushy, but mushy in my mind is kind of negative. The key to accomplishing this is to let your bread soak in the custard only 30 seconds per side, but then move it to a rack to sit for another 2 minutes further. This extra set time allows the custard to penetrate deep inside the bread, and be distributed much more evenly.

The final trick to getting a nice crispy crust, is to cook it twice. First in the pan/griddle as you normally would, but then 5 minutes in a 375 F oven on a rack. This brief oven stint crisps up the exterior nicely.

I highly suggest watching Alton Brown's Good Eats: French Toast episode. That's where I learned the oven trick, and his recipe hasn't done me wrong since.

Regarding challah, I've never had it, but based on the Wikipedia description it sure sounds like a good candidate. Just make sure you slice and stale it overnight.

The official position of the USDA is that all fish must be heated to 145°F (63°C), else it is considered undercooked. In practice, most people don't do it, because fish is terribly overcooked at this temperature, and they seem to mostly live through it without ill effects. With salted fish, there is even less actual risk of foodborne illness. Still, I don't think that anybody will assume the responsibility to tell you that it is "safe" when the responsible officials say it isn't. You are taking a risk, but none of us can quantify it or tell you if it is justifiable. Food science books often recommend preparing fish at temperatures lower than 63°C, but include a disclaimer that this is against food safety guidelines.

A lower oven temperature can definitely produce a better result for your problem, because slower, more gradual heating means that you have a lesser heat gradient within the piece of fish. This means that the thin parts will overheat less in the time the center of the thick parts reaches 40°. However, this will only alleviate the problem, not eliminate it completely, unless you go for a very low temp cooking method like sous vide. If the lower oven temperature isn't enough for you, you might try other tricks to eliminate the problem, like changing the shape (e.g. by creating rolls of fish).