Breakfast is the thing at Sugar, a new eatery in Montauk, which has design-your-own bowls of cereal and fresh-made donuts daily, as well as sundaes and milkshakes. It is open daily from 8 a.m. to 9 p.m. and is downtown on South Edison Street. Dan’s GrillHampton, a cooking competition and tasting event at which eight East End chefs will compete against eight chefs from Manhattan, will take place tomorrow night at the Fairview Farm at Mecox in Bridgehampton.