I bottle all my surplus tomatoes as passata. You can bottle plums, pears, apples, you can bottle juices. The main thing with bottling is to make sure that all your jars are first washed very clean, replace the rubber seals each time they are used, when the jars are washed clean, scald them in hot water to make sure they are free of bacteria, I put mine into the oven at 100 c upside down on the rack to keep them warm and sterile until I am ready to fill them. When bottling anything, it is important that you put some kind of acid into the mixture to stop the growth of botulism. In savoury you can put in vinegar, balsamic vinegar or lemon juice, and fruits you could put in lemon juice or citric acid in powder from you can get from brew shops or the chemist, it is a small risk but well worth taking the trouble to avoid it, although cooking afterwards will destroy botulism, unless you want to eat your fruit cold. I have been bottling for 25 years and I'm not dead yet. I much prefer this method of preservation to freezing, so convenient. Everything will need preparation so I couldn't say what is the easiest thing, plums need stoning,apples and pears core and slice make a solution of 1 lb sugar to 1 pint water bring to the boil and put the fruit in for a couple of minutes just to soften them up (you don't have to but I found this helps to pack the fruit into the jars and stops the problem of fruit floating as it shrinks), pack the hot jars with the fruits, tamp down and fill to the top with the hot syrup. Seal and then put into a hot bath of boiling water for between 10 and 20 minutes, take them out, put them on their sides until cool.
(helps to make a good vacuum). Other fruit variations, apple and rasberry, blackberry or elderberry is very nice