Pound all the ingredients together in a mortar with a pestle until smooth. (Alternatively, combine the ingredients in a food processor and pulse to form a smooth paste.) Heat the sauce in a wok over medium heat, bring to a boil, then reduce the heat and simmer until thickened. Remove from the heat and cool.
To Make the Spring Rolls:
Heat the oil in a wok over medium head. Add the jicama and oyster sauce and sauté for 30 seconds. Remove from the heat and set aside to cool.
Soften a spring roll wrapper in warm water and lay out on a work surface. Put a little of the lettuce, bean sprouts, pork rind, fried shallots, and jicama in the center of the wrapper. Add a little sauce and top with a slice of roasted pork and 2-3 shrimp slices. Fold the bottom of the wrapper up and over the filling. fold the left and right sides in to create a package. Roll the package up toward the top and brush a little water on the top edges of the wrapper to stick the package together. Repeat until you have used up all the fillings. Cut the rolls in half and serve with the remaining sauce.
Recipe courtesy of Quick and Easy Thai Food by Jean-Pierre Gabriel. Get the book here: https://www.amazon.com/Quick-Easy-Thai-Jean-Pierre-Gabriel/dp/0714873225.