Rule: Don’t mess with a good thing.

Exception: Ice Cream Lab, the new liquid nitrogen ice cream parlor that gives prefrozen scoops the cold shoulder.

Opening Friday, the Beverly Hills concept is the brainchild of Tommy Ngan, who encountered the technique in Hong Kong, and his childhood pal, Joseph Lifschutz.

Sidle up to the counter, select a base (cream, nonfat yogurt), and choose from a menu of rotating seasonal (berry tart, olive oil popcorn) and house (blue velvet cupcake, apple pie with graham cracker crumbs) flavors. Displaying a bit of culinary theatrics, a “lab tech” then blasts the ingredients with liquid nitrogen until they reach creamy, frozen perfection.

Order to go or stick around and enjoy Intelligentsia java and free Wi-Fi.

When your treat starts to melt, get it refrosted for free.

That’s not just smoke up your *ss.

Ice Cream Lab, 9461 South Santa Monica Boulevard, between North Rodeo and North Beverly Drives, Beverly Hills (310-795-6505 or icecreamlab.com).

Photos: Biz Urban Photography for DailyCandy