Heat oven to 400°F. In food processor bowl with metal blade or in blender, place chopped dill weed, oil, walnuts, lime juice, garlic, mustard, 1/2 cup of the cheese, the salt and pepper. Cover; process, stopping once to scrape side of bowl, until smooth.
If salmon has skin or bones, remove them; rinse fillet and pat dry with paper towel. Cut salmon into 24 (1-inch) cubes.
On cutting board, roll 1 pie crust into 12-inch round. Cut into 4 rows by 3 rows to make 12 (4x3-inch) rectangles. Repeat with remaining crust. (Rectangles cut at edge of crust will have rounded side.)
Spoon 1 level teaspoon dill pesto onto center of each rectangle; top with 1 salmon cube. Bring 4 corners of each rectangle over filling to center and pinch at top; pinch corners, leaving small openings on sides to vent steam. (For rectangles with rounded side, bring 3 points together at top, pinching to seal.) On ungreased large cookie sheet, place pastries 1 inch apart.
Bake 20 to 25 minutes or until golden brown.
Place remaining pesto in small resealable food-storage plastic bag. Cut small tip off 1 bottom corner of bag; squeeze bag to drizzle pesto over serving plate. Place pastries on serving plate. Sprinkle pastries with remaining cheese and garnish with dill weed sprigs. Serve warm.