Who were the owners of eateries which had highest health hazard by improper cooking time or temperatures?
owners of eateries refer to owner_name; highest health hazard by improper cooking time or temperatures refers to risk_category = 'High Risk' and description = 'Improper cooking time or temperatures';
SELECT T2.owner_name FROM violations AS T1 INNER JOIN businesses AS T2 ON T1.business_id = T2.business_id WHERE T1.risk_category = 'High Risk' AND T1.description = 'Improper cooking time or temperatures'