Try this.

Lay out a large piece of aluminum foil. Put the fish on the foil. YOu can do anything else you have time for -- put some sliced onion under or over it, sprinkle on pepper and squeeze a little lemon juice over it, a little thyme, garlic, as much or little as you like.

Seal the foil well on all sides and place the packets on a baking sheet in case of leaks.

Place in the oven. I'd try maybe 350 degrees or so.

Go walk the dog.

The fish will bake well, be moist and stay that way for a very long time. I figure with frozen flounder 20 minutes would be enough, but if you're gone longer, no problem.

Be very careful when you open the foil. The steam will be hot!

And if you have vegetables like frozen peas or matchstick carrots, you can cook those the same way or even add some to the fish packet.

Throw some little potatoes on to boil and you got supper.

I put frozen meat in the oven all the time.  It never occurred to me that maybe I shouldn't.      I am just lazy when it comes to planning ahead, so the meat is never thawed at supper time. 

wow - this is cool.  After all these years of defrosting.....  No more excuses for "nothing for dinner"!!     

seriously, I could eat toast and garlic stuffed olives and be satisfied.  I don't need a traditional meal every night. I wish my family felt the same way.  I think I could live on tomato soup!  Easy and cheap. 

Hi Karen, 

Thanks for the not so dumb question. I never cook fish and a couple of weeks ago I picked up a small package of tilapia filets. They are in the freezer and I didn't have a clue what I was going to do with them. I thought fish would be good to have since Hubby and I are both trying to lose weight.

R.E. - thanks for the reply...now I know what I will try for supper tonight!

Debbie

Put Lemon Pepper spice - my husband thinks it's the only one to use.  (He grills in the George Foreman or outdoors tilapia, salmon, trout....) 
Another spice I found that I love - I get it at the outlet mall store Kitchen Collection - there are 4 different spices in one jar (separate lids) - Tuscany, Parmesan, Rosa Maria & Sicillian Blend. I mix it in olive oil and use it on cooked veggies, chicken, pasta salads - oh, it's sold as a bread dip!  It's only $5.99 at the Kitchen Collection.  I was really upset when our small town store didn't have any, so when I traveled to a bigger outlet, I bought 3 jars!  They have other spices that are excellent to use - with onion pepper, garlic pepper, orange pepper and lemon pepper in a 4-way jar.

Okay....I was inspired by this thread to try something new.  I had some frozen tilapia filets that I seasoned with lemon pepper, wrapped in foil and baked in the oven.  I cooked it at 350 for 40 minutes, since they were frozen when they went in.  Heated some corn and made some rice.

My husband actually liked it.  A little too much lemon pepper for him, but the fish had a good flavor.  And he doesn't usually care for fish, other than catfish.  The corn was good.

I tasted the fish......      It tasted like dirty feet!  (Not that I've ever actually tasted FEET....but I could imagine!)  One bit just about did me in for the night.

And I have the worst chronic case of "can't make rice to save my life-itis" EVER!  I think I just need to go ahead and pay the extra $$$ for Uncle Ben's!

So, I ended up with PB&J for dinner.  DE-LISH!