Much ink has been spilled in local media about "Prime," the name of a 2,500-pound Black Angus bull who lives on a Kentucky farm and sires all day (actual process not as romantic as advertised). 

Prime's seed is our gain: Beef from his offspring can be had at David Burke Primehouse, the River North steakhouse perhaps most notable for its impressive Himalayan salt-lined dry-aging room.

This is the temperature- and moisture-controlled locker where meat is kept and refrigerated, slowly transforming from simple slabs of beef into beef to the nth power. Two things happen here: Moisture evaporates, which causes the meat to shrink and concentrate its flavors. Meanwhile, connective tissues break down, tenderizing it. The smell of the dry aging room is like breathing in an atmosphere of truffles.

Executive Chef Rick Gresh said he experimented with different stages of dry aging and found 40 days of dry aging ideal for his burger -- imparting subtle blue cheese and mushroom flavors in the meat. 

After charbroiling the patty at 900 degrees F, it's plated on the toasted potato bun, slathered with bacon mayonnaise and topped with pan-fried, garlicky spinach and crispy shallots. Gresh said those ingredients are the mainstay dishes of a steakhouse (baked potatoes, creamed spinach et al.), which he wanted to re-create on a bun. 

Biting in, the texture is a trip -- creamy, crispy, warm and tender, a hit of smokiness from the bacon, and the juices from the unctuous beef patty induce your eyes to shut as you savor the moment privately.