Heat 4 T. butter in large skillet over medium heat. Add onion and garlic and saute until very soft, but not browned, about 5 minutes. Add mushrooms; saute until tender and juices have evaporated, about15 minutes. Stir in bread crumbs; cook, stirring to blend, about 3 minutes. Add dried fruits, 2 T. lemon juice, and half the salt and pepper. Let stand until cool enough to handle.
Heat oven to 350 degrees.
Rinse turkey breast and pat dry. Trim any veins or tendons. Using fingers and tip of small paring knife where needed and working from wide end, separate skin from flesh to create pocket for stuffing.
Place turkey in baking dish just large enough to hold it. Sprinkle all over with remaining lemon juice, salt, and pepper.
Spoon all but 1 cup stuffing under skin and in neck cavity (small end). Secure skin to flesh with small skewers. Fold under skin at neck end. Spoon remaining 1 cup stuffing onto underside of breast and turn skin side up in dish. Rub skin with remaining 1 T. butter.
Roast, basting every 15 minutes with pan juices, until meat thermometer inserted in thickest part of breast registers 160 degrees, about 1-1/4 to 1-1/2 hours. Pour pan juices into liquid measuring cup. Let turkey rest for about 15 minutes.
Spoon off fat from pan juices and add enough water to measure 1-1/2 cups. Strain into small saucepan and heat to simmering. Dissolve cornstarch in cold water; stir into pan juices. Simmer, stirring constantly, 1 minute. Remove from heat and adjust seasonings. Carve turkey into 1/2-inch-thick slices; serve with gravy (and a nice Zinfandel!).