Preheat oven to 350 degrees F. Adjust oven rack to middle position. Grease or spray a 9x5-inch loaf pan.
In a bowl combine the diced rhubarb, sugar, cinnamon, and lemon zest; set aside. Set aside 1/4 cup of rhubarb mixture and some of the chopped pecans.
In a large bowl, sift together the flour, baking soda, and salt; set aside.
In the bowl of your mixer, add the egg and lightly beat. Add the brown sugar, vegetable oil, and vanilla extract; mix until well combined.
Add 1/2 the flour mixture and 1/2 the buttermilk and beat until smooth. Add the remaining flour and buttermilk and continue beating until smooth.
Stir in the rhubarb mixture and the chopped pecans.
NOTE: Bake all quick breads as soon as the ingredients are assembled. Since high temperature are often called for, it is best to bake them in the center of the oven, as the heat in the top third of the oven will be too intense.
Pour batter into the prepared loaf pan and then sprinkled remaining reserved rhubarb mixture and some chopped nuts over the top (for nice effect when bread is finished baking).
Bake approximately 50 to 55 minutes or until a toothpick inserted in the center comes out clean. A good check is to use an instant digital thermometer to test your bread. The internal temperature of the bread should be at 200 degrees F.
When done, remove from oven and cool on a wire rack 10 minutes; remove from pan. Cool completely before slicing.
Storage: Breads that contain fruit, nuts, or butter may be stored for 2 or 3 days, well wrapped in plastic wrap or aluminum foil. May be frozen for longer storage. After thawing frozen breads, reheat them in a 400 degree F. oven for a few minutes before serving.
Makes one loaf or two small loaves.
* Look for thinner stalks as they will be more tender and less fibrous than thicker stalks. If using frozen rhubarb, be sure to drain off and discard the liquid after thawing.
** Learn how to make a Buttermilk Substitution.
Rhubarb Nut Bread Recipe: https://whatscookingamerica.net/bread/rhubarb-bread.htm