Use a small.
How to seal siding to concrete.
Buy yourself a caulking gun learn how to mount and open a tube of caulk and go to it.
Most ties when it s used in construction it s completely covered by siding or similar.
Since some of the siding looks like it will need re priming and painting make sure that you use a paintable type of caulk.
If you go inches which you should install aluminum flashing for example.
If your concrete is new you ll need to let it cure wait at least one month before applying sealer.
Crawl around the exterior of your home and use a flashlight to find cracks holes and gaps.
The best solution here may be to clean up that area of all debris let it be fully dry and then apply a bead of qood quality exterior grade caulking material.
Note that there are various types of caulk.
How to seal siding to keep out mice.
Find the entrances mice use to enter your home.
The temperature also needs to stay above 50 f during application and drying time up to three days.
Theoretically you could seal the tar paper to the foundation with foam spray caulking something similar.
Not a vapor barrier as you say but it prevents water that makes it past the siding from getting any further into the wall.
Sealer needs to be applied in dry conditions because it won t adhere to damp concrete.
Look under the siding at the area meeting the foundation of your home for holes and gaps.
Might be good but it s more designed for sealing air insects and separating wood from concrete.
It will eventually degrade if exposed to sunlight.
I believe you have tar paper under your siding based on your description.