In a large skillet, melt margarine. Add onion, garlic and mushrooms. Saute until tender but not browned. Add tarragon; stir until it is softened. Pour mixture into bowl of a food processor fitted with steel blade. Add remaining ingredients. Process until mixture is smooth. Add cheese if you prefer a more spreadable consistency. Spoon into serving bowl. Top with garnish of your choice.
Variations:
Substitute other vegetables for the mushrooms; one of my favorites is broccoli
Substitute 1/2 teaspoon fennel for the tarragon and 1 cup whole pecans for the
almonds