Freezing is probably the easiest way to prepare a supply of tomatoes. In season, buy a large quantity of them or grow your own. At other times of the year, look in the reduced food bin for bags of tomatoes priced for quick sale.
Blanch to remove skin – or not
If you’re a purist, heat a pot of water to boiling. Keep it simmering and put the washed whole tomatoes in it for 20 seconds or so (blanching). Use a big slotted spoon to put them in and take them out. Run cold water over them to stop the blanching and cool them. Then cut the core out and use your small knife to gently peel the skin off. It should just slide off. Plum tomatoes are especially easy to peel, and make the best tomato sauce. If, like me, you’re not a purist and don’t mind pieces of tomato skin in your sauce, just wash the tomatoes and cut the core out.
Cut – or not – and cook
Then half or quarter the tomatoes or, best for flavour retention, leave them whole and cook them. Add a tiny bit of water to your pot in order to keep the tomatoes from burning or, better yet, turn the heat on very low until they cook a bit and produce their own liquid.
You can add herbs and seasonings to the pot or just leave them so you can flavour them later when making the final product. Cook them, stirring occasionally, until they are soft. The length of time depends on the amount of tomatoes, the size and the degree of softness you want. Figure on an hour to an hour and a half for a large pot.
When they’re done, open a large size freezer bag and stand it on end. You can also put it in a container, like a tall milk pitcher.
Fill freezer bags
Use your large slotted spoon to carefully spoon the tomatoes into the bag. The pitcher averts spilled tomatoes all over your counter until you get the hang of spooning and holding the bag upright at the same time. Two people doing this can also avoid accidents. Fill the bag about half full. Zip it up and it should lay almost flat.
Make sure the outside of the bags are dry so they don’t freeze together, and lay them flat on top of each other in your freezer, and presto, tomatoes ready for sauce-making. Each bag is about equivalent to a large can of tomatoes. At harvest prices, four bags cost about the same as one can.
You’ll have tomato-flavoured water left. You can freeze it in small containers and use it like you’d use any vegetable stock, in soups or stews.
Freeze uncooked whole tomatoes
You can freeze uncooked whole tomatoes too – blanch and peel them if you like or just pull the stem off and wash them. Put them in the freezer on cookie sheets, making sure they are not touching. After they’ve frozen, bag them up and put them back in the freezer. You won’t be able to use them as “fresh” tomatoes, like in salad, but they’re fine for cooking. The only disadvantage is they take more freezer space than cooked ones do.
Two caveats about home-made frozen tomatoes. One: the slight thickness of the liquid that is in canned tomatoes isn’t there. I don’t know what is in canned tomatoes to give that, and I like it for helping the texture of your final tomato sauce. You get the same thing from home-canned tomatoes. Maybe it’s the heat-retention from long cooking. Maybe that’s what “stewing in your own juices” means. To approximate it with frozen tomatoes, I’ve added a bit of flour or cornstarch in the final sauce. I’ve also added canned tomato soup or tomato paste thickened with a bit of flour or cornstarch. You just want something that makes your sauce less watery.
Two: I watched Chef at Home once when chef Michael Smith was talking about tomato sauces. He prefers canned tomatoes over fresh because the lag time between picking and processing is less. Canned tomatoes, he said, literally are picked in the field and canned next door, within a very short period of time. Therefore, they are at the height of ripeness and freshness. He also prefers canned whole tomatoes rather than diced. Whole tomatoes, he said, require only one cooking process in their canning whereas halved or diced tomatoes require two. In your cooking, you ‘process’ them yet again, and each time they lose nutrients. So, despite the appeal of fresh tomatoes cooked slowly into a lovely pasta sauce, you’re actually better off with a can. Who knew?
If money is as much an issue as nutrients, there is a compromise. Supplement your store-bought can with cheap fresh (or frozen or home-canned) tomatoes.