If you really want to impress your summer barbecue guests, treat them to one of these gourmet burgers: http://www.dailymail.co.uk/femail/food/article-1197009/The-perfect-burger-experts-Seven-chefs-reveal-secret-hamburger-recipes.html . The photos alone are enough to make my mouth water.

If you're serious about cooking one of these gourmet burgers, you might need this metric to US conversion cooking table: http://www.botanical.com/botanical/cvcookix.html . Let me know how it goes. Mmm.