How to Make It
Preheat the oven to 350°. In a food processor, pulse the graham crackers with 1/4 cup of the sugar and 1/4 teaspoon of salt until fine crumbs form. Add the butter and pulse until incorporated. Press the crumbs evenly over the bottom and up the sides of a 13-by-4-inch fluted tart pan with a removable bottom. Bake the crust for about 12 minutes, until fragrant and browned. Transfer to a rack and let cool completely.
Set a fine sieve over a medium bowl. In a medium saucepan, whisk the egg yolks with 1 cup of the sugar until well blended. Whisk in the vinegar, cornstarch and 1/2 teaspoon of salt and cook over moderate heat, whisking, until the mixture just starts to bubble, about 5 minutes. Add the raspberries and return to a simmer. Simmer over moderate heat, whisking, until the berries are broken down and the filling is very thick, about 5 minutes longer.
Remove the saucepan from the heat and whisk in the coconut oil. Strain the custard through the fine sieve, pressing on the solids; there should be just over 1 cup of custard. Pour the custard into the crust, cover with plastic wrap and refrigerate until cold, at least 2 hours.
Transfer the tart to a platter. In a large bowl, whisk the cream with the remaining 1 tablespoon of sugar until medium peaks form. Dollop the whipped cream on top of the tart, garnish with berries and serve.