There is no as per say restrictions for Vasculitis however I presume you are on steroids ( high dose) and possibly steroid sparing agents such as Azathioprine , mycophenolate or methotrexate .In that case avoid certain foods which may interact the medications. Usually plant based diet is helpful particularly Turmeric,Ginger,garlic,cayenne pepper are quite good. Beside reducing the excessive salt and fatty food intake , excessive Red meat consumption should also be avoided, white meat such as chicken is fine. Vasculitis is an umbrella term for atleast 50 closely related conditions and depending upon type( IgA vasculitis, ANCA Associated vasculitis, large vessel vasculitis, SLE related vasculitis etc)it affects particular organs. You may need to emain vigilant about warning signs and regularly see your qualified Rheumatologist.