To the bowl of a stand mixer fitted with a dough hook, add the yeast, ¼ cup warm water, and a pinch of sugar and set aside until foamy, about 5 minutes. Add ¼ cup of sugar, the eggs, sour cream, and 6 tablespoons of the melted butter, followed by the flour and salt. Mix on low speed until a dough begins to form, 2–3 minutes. Increase the speed to medium and continue mixing until the dough is very smooth and elastic, 3–4 minutes more. Remove the dough hook, cover the bowl with plastic wrap or a lid, and set aside in a warm place until the dough has nearly doubled in size, about 2 hours.
Meanwhile, in a medium bowl, stir together the remaining ¾ cup sugar, ¾ cup pecans, and the orange rind and set aside. Butter the inside of a 9- by 13-inch rectangular baking dish and set aside.
Lightly flour a clean work surface and turn the dough out onto it. Knead the dough lightly a few times to deflate, then, using a bench scraper or large chef’s knife, divide in half. Roll each half into a loose ball, cover, and set aside until the dough has relaxed slightly, about 5 minutes.
Lightly flour a rolling pin and sheet one of the dough balls out to an even, 12-inch circle. Brush the surface with 1 tablespoon of the melted butter, then sprinkle evenly with half of the reserved sugar-pecan mixture. Cut the circle into 12 triangular wedges. Starting from the wide end, roll one of the wedges in towards the center (like rolling up a croissant). Press down lightly on the point to flatten slightly. Repeat with the remaining wedges, then with the second dough ball, then transfer the rolls in 3 rows, point-side-down down, in the prepared baking dish. Cover with plastic wrap and set aside in a warm place until the rolls have grown into each other, and are very gassy and doubled in size, 1–1½ hours.
Meanwhile, preheat the oven (with one of its racks positioned in the center) to 350°F. When the cake has risen, uncover and bake until evenly golden brown and cooked through, 30–35 minutes.
Glaze the cake: In a small pot over medium heat, whisk together the sugar, sour cream, butter, and orange juice. Bring to a boil and cook, stirring occasionally, until smooth and glossy, about 3 minutes. Remove from the heat and pour the hot glaze over the coffee cake. Sprinkle with the remaining ¼ cup of pecans. Cut into squares and serve warm or at room temperature.