You could use tomato sauce, tomato paste with added liquid, or crushed tomatoes.
If you are cooking with them, you can use canned tomatoes. If you are using them in salads, or on sandwiches, etc., then there really is no substitute for a raw tomato.
Tomatoes, and Sauce.
You can boil down tomato sauce on the stove. You can also blend crushed or whole tomatoes and boil down to 2/3s the sauce.
It is a canned tomato product where the tomatoes were cooked with onion and celery and sometimes spices before canning.
To cook your fresh tomatoes into a sauce or a paste, chop and blend them. Cook in a wide pan on medium low until the tomatoes have reduced to a sauce or paste according to your liking stirring constantly Season with salt and a bit of sugar if necessary. Careful to not burn.
Ketchup is spiced tomato sauce cooked with vinegar. Tomato sauce is the sauce made by cooking tomatoes down until the meat of the tomato breaks down into a sauce consistency. Ketchup is spiced tomato sauce cooked with vinegar. Tomato sauce is the sauce made by cooking tomatoes down until the meat of the tomato breaks down into a sauce consistency.
You can use crushed tomatoes instead, or there are some white Pizza sauces available from all good supermarkets.
tomatoes
Tomato sauce
Tomato sauce is cooked to allow the liquid in the tomatoes to reduce which creates the sauce or paste. Tomato ketchup is cooked tomatoes with added ingredients such as vinegar, sugar, salt, and other spices.
Tomato juice is acidic