Thank you for your question.  When you say "oak mulch," are you referring to oak tree leaves, or to the bark chips from oak trees?  Most gardeners don't use bark chips in their vegetable gardens, but use them around ornamental plants.  Oak leaves, however, are a fine mulch around vegetables.  If you'll provide more information, I'll try to give you more specific advice.  Thank you.

I am referring to the bark chips. Thank you Eva Temepleton

Thanks, Eve. Oak chips are safe to put in vegetable gardens, but they need to be removed after every harvest. Oak leaves can be tilled under the soil, and they become valuable nutrients, once composted, for future gardens. Bark chips take years and years to break down.