How to Make It
Prepare the Streusel: Preheat oven to 350°F. Stir together pecans, flour, brown sugar, salt, cardamom, and nutmeg in a small bowl; stir in melted butter until completely combined. Set aside.
Prepare the Bread: Whisk together sugar, melted butter, sour cream, orange zest, and juice in a large bowl until well incorporated; whisk in eggs until well incorporated. Whisk together flour, baking powder, salt, baking soda, cardamom, and nutmeg in a medium bowl. Fold flour mixture and rhubarb into sugar-butter mixture just until combined.
Spoon mixture into a well-greased (with shortening) and floured 8 1/2- x 4 1/2-inch loaf pan. Sprinkle top evenly with Streusel, and bake in preheated oven 55 to 60 minutes, tenting bread with aluminum foil after 40 minutes to prevent overbrowning. Transfer to a wire rack, and let cool in pan 10 to 15 minutes. Transfer from pan to a serving plate, and cool at least 1 hour before slicing.