1. Place salmon fillet in pan and just cover with cold water. Bring to a boil, then reduce heat and simmer for 5 minutes. Remove from pan and cool completely on a plate, about 30 minutes.
2. Place salmon in food processor and pulse briefly. Add cream cheese, butter and lemon juice; puree until smooth. Season with salt and pepper. Transfer to a bowl, cover and chill for 30 minutes. (Can be made to this point the day before.)
3. Spoon pâté into piping bag with star nozzle and pipe onto vegetables or crackers; sprinkle with chopped chives. Or spoon it into a serving bowl and serve with crudités.