Smoke Signals

Line heavy large pot with heavy-duty foil. Sprinkle wood chips over bottom of pot; cover. Turn exhaust fan on high. Heat pot over high heat until smoke begins to form inside pot. Fill 9 x 4 1/2 x 3-inch metal loaf pan with ice. Place in pot; cover tightly. Smoke ice until just melted, about 5 minutes. Remove from heat. Cool slightly. Cover loaf pan tightly with plastic wrap; freeze until firm, at least 6 hours. Using ice pick, cut ice block crosswise into 4 large smoked ice chunks. Wrap tightly in plastic and keep frozen.
Bring 1 cup water and sugar to boil in medium saucepan over high heat, stirring until sugar dissolves. Add pecans; reduce heat to medium and simmer until syrup tastes like pecans, about 12 minutes. Strain; discard pecans. Cover and chill pecan syrup until cold, about 2 hours.
Place 5 tablespoons whiskey, 3 tablespoons Sherry, 1 tablespoon lemon juice, and 3 tablespoons pecan syrup in cocktail shaker. Fill with plain ice cubes; cover and shake until cold. Divide mixture between 2 old-fashioned glasses. Repeat with remaining 5 tablespoons whiskey, 3 tablespoons Sherry, 1 tablespoon lemon juice, 3 tablespoons pecan syrup, and ice. Place 1 smoked ice chunk in each glass and serve.