In a mixing bowl, combine flour, sugar, and salt. Add cold butter and mix until crumbly. Add egg yolk and ice water, mix until dough forms. Press into tart pan. Bake for 15 minutes.
In another bowl, whisk together sugar, eggs, lemon juice, lemon zest, and heavy cream. Pour into baked crust. Bake for another 15 minutes or until set.
Let tart cool. Top with mixed berries. Serve chilled.