For the dough: Combine the butter, milk and orange juice in a small saucepan over low heat and cook, stirring gently, until the butter is just melted. Remove from the heat and allow to cool to lukewarm. (You can also do this in a measuring cup in the microwave.)
Combine the flour, granulated sugar, instant yeast, salt and cinnamon in a large bowl or bowl of a stand mixer fitted with a dough hook and whisk to combine. Add the milk mixture and eggs, then mix with the dough hook until the dough is smooth and slightly sticky, 7 to 10 minutes. (Alternatively, this can be mixed in a large bowl and turned onto a work surface to knead by hand.) Transfer to an oiled bowl, cover with plastic wrap and allow to rise until the dough has doubled in size, about 1 hour 30 minutes to 2 hours.
Meanwhile, make the brown sugar filling and caramel.
For the brown sugar filling: In a small bowl, combine the brown sugar, cinnamon, salt and orange zest and rub together with your fingers until everything is evenly combined. Set aside.
For the tahini caramel: In a 3 1/2-quart enameled braiser over low heat, add the brown sugar, milk, tahini, butter and salt. Whisk to combine. Increase the heat to medium and bring to a boil. Allow the caramel to boil until it begins to darken in color, 2 to 3 minutes. Remove from the heat and add the vanilla. Allow to cool until it is just warm to the touch. (Alternatively, the caramel can be prepared in a small saucepan and transferred to a greased 9-by-13-inch baking dish.)
For the assembly: Turn dough out onto a lightly floured surface and roll out into a 10-by-18-inch rectangle. Schmear the softened butter evenly over the entire surface of the dough with a 1/2-inch border at the top only, then sprinkle over an even layer of the brown sugar filling mixture. Roll up the dough (the long way) into a tight roll and pinch to seal. Slice into 12 even pieces and space evenly in the pan with the cooled caramel. At this point you can cover and refrigerate overnight or cover with plastic and proof at room temperature until puffed up and doubled, about 1 hour to 1 hour 30 minutes. (If refrigerated overnight, remove from the refrigerator and allow to proof at room temperature until puffed up and almost doubled in volume, about 2 hours.)
Place an oven rack in the middle position. Preheat the oven to 350 degrees F.
Bake until rolls are golden (begin checking at 38 minutes). Remove from the oven and allow to cool for a few minutes, but not completely. Carefully invert the rolls onto a serving dish and garnish with sesame seeds and flaky salt. Eat while warm. The caramel rolls will keep in an airtight container at room temperature for up to 2 days.