For the sauce:
1/2 cup heavy cream
4 garlic cloves, crushed
1/4 cup lemon juice
3/4 cup olive oil
2 tablespoons minced fresh dill
2 tablespoons minced fresh flat-leaf parsley
1 pound penne
For the sauce: In a saucepan, bring the cream just to a boil over moderate heat. Add the garlic and simmer the mixture for 15 minutes - until the cream is reduced to about 1/4 cup. In a food processor, puree the mixture until it is smooth. Add the lemon juice and blend the mixture well. With the motor running, add the oil in a slow stream. Blend in the dill, parsley, and salt and pepper to taste.
Cook the penne in a large pot of boiling salted water until it is tender. Drain well and transfer to a large bowl. Toss together gently the penne, the bell peppers, the onion and smoked salmon (reserving some strips for garnish). Add the sauce and toss the mixture gently. Divide the mixture among 4 plates and garnish with smoked salmon and dill springs. Serve warm. Serves 4.