With the Kentucky Derby here and summer entertaining season ramping up, a decades-old icy vodka hack from Martha Stewart is resurfacing for being eye-catching and practical, keeping the bottle ice-cold for hours while on display. The lifestyle icon’s signature “iced vodka” presentation — a bottle of liquor frozen inside a block of flower-studded ice — is making the rounds online again, drawing millions of views and inspiring hosts to try the pretty and practical hack themselves. “Iced vodka is one of my favorites, and I like to make a very beautiful presentation of the bottle of vodka encased in a block of flower-studded ice,” Stewart says in a resurfaced clip of the technique. “It’s real easy to do.” To do it, she places a 750-milliliter bottle of vodka inside a half-gallon milk carton with the top removed, arranges flowers around it, then fills the container with cold water before freezing.…