Preheat the oven to 350 degrees F. To make the crust. In a food processor, pulse the graham crackers and pretzels into semi-fine crumbs. Add the butter and 2 tablespoons honey and pulse until the mixture holds together when pinched and starts to look like dough. Press the dough into an 8 or 9 inch tart pan with a removable bottom to form a flat, even crust. Transfer to the oven and bake until toasted, about 8 minutes. Meanwhile, combine the heavy cream, remaining 1/3 cup honey, and lemon zest in a large pot, bigger than you think you'll need. Set over high heat and bring to a boil. Once boiling, boil 5 minutes and then remove from the heat and whisk in the lemon juice, vanilla, and a pinch of salt. Let cool 10 minutes. Carefully pour the lemon cream into the baked crust. Cover and chill 1 hour or until set. Before serving, remove the tart from the pan and top with fresh berries.