To prepare a vietnamese eggplant with spicy sauce, you'll first need to prepare the eggplant. First, remove the stems and cut off the tops. Cut the skin off of one eggplant and slice it in half lengthwise. Then, cut the flesh into bite-sized pieces. Place the pieces of eggplant in the crock pot and cover with water. Bring the water to boil, then reduce the heat to medium-low and simmer for 30 minutes. Remove the pot from the stove and let it cool for 10 minutes before serving.