Vendor is a lousy word. Think about it. Put your money in, get the product out. Broadline distributors are vendors. Jamison is a farmer and a partner with the chef.
Vendors are machines, partners are people.
Relationships reflect values. If a chef spends his or her time trying to get another nickel off the price of peas, you know what the chef's values are. If he spends time talking to the grower about the conditions in the field after the rain and the effect on the produce, he has an entirely different set of values. Learn from him or her, don't reduce the relationship to order-taking. For that matter, check out their web page.