Wash the collard greens thoroughly in a sink filled with cold water. Remove the stems that run down the center of the greens. Fold over the stem and carefully cut out the tough stems. Stack 6 to 8 leaves on top of one another, roll up, and slice into 1/2 to 1-ince thick slices. Place greens and baking soda in pot with meat and cook covered for 90-120 minutes, stirring from time to time.