Tuna Tarragon Pasta Salad

1 cup mayo/dressing
1/2 cup sour cream
1 T lemon juice/vinegar
1 T dry tarragon
1 T mustard
1 t sugar
2 cans tuna
2 cups peas
1 lb pasta
salt, pepper
Relish - optional

Bake pasta, cool, mix other ingredients separately then pour over pasta and mix evenly