Like Puxatony Phil peeping his head out of a hole to tell us which way winter’s going, chefs today will begin doing free lunchtime cooking demos at the Market & Shops at Comcast Center, signaling that Restaurant Week is on the horizon. First up is Olivier Desaintmartin, chef and owner of Caribou Cafe and Zinc. He’s followed by David LaForce from El Vez, who will be there on Thursday. Next week’s demos will feature Farmers’ Cabinet’s Robert Tyndall (January 17) and Percy Street’s Erin O’Shea (January 19). Chefs and demos are free and get cooking at 12:30 p.m.