To make sauce, in a small bowl, combine sour cream, pickles, and 2 tablespoons of the Ranch dressing mix; cover and refrigerate. Prepare frozen shoestring fries according to package directions. Meanwhile, on large plate, combine bread crumbs and remaining salad dressing mix. Dip fillets in egg, then coat with bread crumb mixture. Fry fillets in 3 tablespoons of oil until golden. (Add more oil to pan if necessary to prevent sticking.) Serve fish fillets with shoestring fries and chilled tartar sauce. Garnish with lemon wedges.