Match words with a specific letter and not another letter

Question

I have a couple of strings and want only words with letter o and not word with letter u.

For example:

• hello
• our
• hey
• owner
• udnwedfo

So it should work on the word hello and owner.

I have tried something like

([^u])?([o])?([^u])

But so far it did'nt work.