I'm not saying my way is right or the only way. It is just how I do it. I wash them, let them dry, and freeze them whole in gallon ziploc type bags. Each gallon bag weighs around 3-1/2 pounds for me with my mix but that may vary for you depending on size and variety.
I have not tried slicing them so I don't know how that works. Hopefully someone will answer that one as I am interested in the pros and cons of that process. Some differences I can think of is getting the skin off and maybe thawing time, but I really don't know.
I only freeze the ones without flaws I don't want in my sauces. When you thaw the tomatoes the skin splits and comes off very easily but the flesh is very soft and mushy. I find it very dificult to properly core them or cut out the bad spots after they thaw, though with a very sharp paring knife I can get most of the core. Since I am running them through a food mill, the core I miss doesn't bother me.
I thaw them in water in the sink, then take the skin off over a bowl. If I handle them gently until I take the skin off, I don't lose any real amount of juice. Some people may be willing to sacrifice the juice to reduce the seeds and make the milling process easier. I probably would not lose that much volume but I think I'd lose flavor doing that. I really don't know as I have not tried it without the juice but it just doesn't feel right to me to not use the juice.
I found a couple of different ways to do this online, it really ends up being when you want to have to do the most work.
Do you want to have to peel, core and slice them before freezing or after?
i cook mine (actually today i'm roasting them in the oven) until they are watery-ish and a bit reduced. then i put them in plastic freezer baggies.. that way i can cook down to whatever i need later in the year. for instance i can use as a base for pasta or pizza sauce, less for chili etc..
The easiest thing (what I do) is to freeze them washed but whole. When you thaw them the skins slip off very very easily. If you will run the resulting sauce product through a food mill to remove seeds, you may as well leave the stem area on when you freeze them. However if you like (or just don't mind) seeds in your finished product, and thus will not be running it through anything to seive out the chunky bits, I would recommend cutting out the stem area before freezing.
Can't think why a person would skin tomatoes before freezing, as one of the major merits of freezing is that it makes the skins come off so easily.
I've never tried freezing cut up tomatoes; they should pack more densely if you are very short of freezer space, but might (?) lose more water and freezerburn a bit more easily, dunno. And of course you would lose the advantage of easy skin removal (tho if you enjoy using a food mill or other straining device, that might not matter too much)
I agree with Pat, I freeze those puppies whole and then just dump 'em in the steam juicer when I'm ready to can. There's a bit more juice to drain off when you freeze them first so be prepared for that either by using a steam juicer or knowing that you'll need to cook your sauce down to reduce the fluid and thicken the final product.
I squeeze the tomatoes to get the juice and seeds out then do a rough dice. I pack them in 1-quart plastic containers (like you get from Chinese take-out) and freeze. Once it's frozen, I dump the quart chuck of tomatoes from the plastic container into a
1-gallon vacuum-freezer bag (take the air out) and then immediately refreeze.
It depends on whether you want the skin in your finished product-if not, I would think you'd want to take the skin off before freezing. We blanch ours (plop 'em in boiling water for a couple - three minutes, dunk 'em in cold water so you can handle them, and pop the skins off).
Then we cut ours in fourths and throw them in a big pot on the smallest burner of the gas stove. Set as low as possible, this simmers them without burning. We cook them down for a day or so, then let them cool and put them in gallon buckets with sealed lids and freeze them. Now we have stewed tomatoes that can be used for anything at all. We make spaghetti sauce, chili, catsup, etc. and there is no prep time for the tomatoes except thawing them. We then freeze the finished spaghetti sauce or chili.
Lots of options! Enjoy - we lost all 85 of our paste tomato plants to the blight this year.
One more thing about those tomatoes and skins and/or pulp. You can dry that stuff-all of it, don't let any of it go to waste and then make a tomato powder that you can add to anything. You can do the same with carrot peels, celery leaves, anything at all that might normally be trash. The ultimate veggie powder is asparagus powder. Mushroom powder, don't forget your fruits, get those peelings drying and use that powder in smoothies or desserts or yogurt.....