Just like Search for singleton tags on questions, it's currently only possible with a SEDE query.
But since there are many tags which don't have any influence on your ability to answer the question, it's probably better to focus on a few tags which you want to exclude, e.g.
[c#] [winforms] -[linq] -[sql]
(results)
You can fork the query to add additional constraints, like no answers at all or no accepted answer. If you're new to SEDE and/or SQL, don't forget to take the awesome tutorial which will help you getting started.