How to Make It
In a large mortar, working in batches, pound the beans in order to lightly smash them; transfer to a bowl. Add the tomatoes to the mortar and pound them briefly; add the tomatoes to the beans in the bowl.
Add the dried shrimp, peanuts, chiles, garlic, salt and sugar to the mortar and pound to a coarse paste. Stir in the lime juice and fish sauce until blended. Add the dressing to the smashed beans and tomatoes and toss thoroughly.
Line a platter with the lettuce and spoon the bean salad on top. Arrange the cabbage wedges around the salad and serve.