Add dry ingredients: flour, salt, baking powder. (DO NOT ADD BAKING SODA)
In a separate bowl mix sour cream or plain greek yogurt and baking soda. Wait until it begins to react, then add to batter and incorporate gently.
In another separate bowl, mix pecans, sugar and cinnamon.
Assembly: In a greased 11x15" pan, spread half of batter on bottom. Sprinkle with half of cinnamon sugar mixture. Spread last of batter on top. Sprinkle evenly with the remaining cinnamon sugar mixture.