Bring a large saucepan of water to a boil. Add the tomatoes and blanch just until the skins loosen, about 30 seconds. Using a slotted spoon, transfer the tomatoes to a large, rimmed platter to cool slightly. Slip the skins off the tomatoes. Halve the tomatoes crosswise and squeeze out the seeds. Quarter any large tomatoes and pack into 4 hot sterilized 1-pint jars, stopping 1/2 inch from the top. Bury 2 basil leaves in each jar and add 1 tablespoon of lemon juice and 1/2 teaspoon of salt. Use a knife to release any air pockets. Wipe the glass rims and close the jars. Set them in a water bath and bring to a boil. Process for 1 hour and 25 minutes.