15 Romolo lets you eat its burger "yo mama style" with peanut butter and bacon. Heirloom Cafe tops its off-menu beauty with pungent Epoisses cheese. Chef Bruce Hill hand-designed a burger weight to evenly cook the patties at Bix. Hayes Valley's Straw serves its ground beef mounded on a donut. As any of these restaurants will tell you, when it comes to surviving the stiff burger competition in SF, you've gotta have an angle.