8 cups assorted fresh fruit, such as halved, pitted, and sliced stone fruit and berries
Sweetened whipped cream
Directions
Stir sugar and water in heavy medium saucepan over medium-high heat until sugar dissolves. Scrape seeds from vanilla bean into sugar water; add bean. Bring to boil. Place candy thermometer into mixture so that bulb is submerged. Boil until thermometer registers 260°F, occasionally swirling pan and brushing down sides with wet pastry brush, about 8 minutes (time will vary due to size of pan). Remove pan from heat and add plums to pan; let stand 1 minute. Stir mixture constantly over high heat until plums are broken up, spoon leaves path when drawn across bottom of pan, and mixture is reduced to 1 1/3 cups, about 9 minutes. Transfer to metal or glass container. Press plastic wrap directly on surface of jam and refrigerate until cool.
DO AHEAD Can be made 4 days ahead. Keep refrigerated.
Finely grind hazelnuts with 1/2 cup flour in processor. Transfer to medium bowl. Whisk in remaining 1 cup flour, sugar, and salt. Make well in center and pour in melted butter. Mix with fingers until moist crumbs form. Transfer mixture to 10-inch-diameter tart pan with removable bottom. Press mixture firmly onto bottom and up sides of pan. Freeze crust 30 minutes.
Preheat oven to 350°F. Bake crust until golden brown, about 35 minutes. Cool crust 15 minutes. Maintain oven temperature.
Brush bottom and sides of tart with 1/2 cup plum jam. Return to oven and bake until jam bubbles all over, about 14 minutes. Cool completely.
DO AHEAD Can be made 8 hours ahead; cover and let stand at room temperature.
Place all fruit in large bowl. Stir remaining plum jam to loosen and add to fruit in bowl; toss gently to coat. Transfer fruit to crust, mounding in center. Serve with whipped cream.
