Legal Question in Landlord & Tenant Law in Illinois

If by harassment you mean applying rules that are in effect, so long as there is an opportunity to confront the accuser (some kind of due process), yes. What constitutes some offensive cooking odor to one person is another's odiferous delight......unless there is more going on here, like constant cooking of extremely pungent ingredients, or possibly an illicit catering business being run from the home. A lot depends on a lot of additional information.

It depends on what you mean by harassment. It is common for HOAs to have rules about noxious odors and they are generally allowed to enforce those rules.