I find the best way to keep them is to store them in olive oil.
150g sundried tomatoes
2 slices lemon
Put a third of the tomatoes into a large jam jar, then a slice of lemon, repeat this again, then finish of with the remaining tomatoes.
Then pour in enough olive oil to cover the tomatoes completely.
Put the lid on the jar and gently rock the jar to make sure that the olive oil has filled all of the cavities between the tomatoes.
After about 3 weeks, I empty the contents into a bowl remove the lemon slices and then return the tomatoes and the oil to the jar. I find that the tomatoes will keep for several months in the oil, but the lemon does not.
Tomato Infused Oil
Once you start to work your way down the jar of tomatoes, don't throw the oil away.
Pour off into a cup the excess oil, leaving enough oil to cover the remaining tomatoes in the jar.
The oil you have in the cup can be strained to remove the sediment, then put in a bottle to be used as infused oil in cooking.