1, To make the dressing, in a small bowl, combine the lime juice, sugar, fish sauce, water, and chiles and stir to dissolve the sugar. Set aside to develop the flavors.
2, Trim off the ends of each cucumber, and then halve lengthwise. Use a teaspoon to remove the seeds from each half (the English cucumbers will have few seeds). Cut the halves crosswise into slices a scant ⅛ inch thick. A razor-sharp knife or a Japanese Benriner slicer produces the most attractive, uniformly thin slices. A food processor can be used but will yield less satisfactory results. Put the cucumbers and carrot in a large bowl, add 1 ½ teaspoons of the salt and the sugar, and toss to mix. Set aside for 30 minutes to weep. A pool of juice will accumulate at the bottom of the bowl.
3, Drain the cucumbers and carrot in a colander and place under cold running water to rinse off as much salt and sugar as possible. Working in batches, wring out excess moisture in a nonterry dish towel: position a mound of the vegetables in the center, roll it up in the towel, and then twist the ends in opposite directions to force out the liquid. Do this 3 or 4 times. You want to extract enough water from the cucumber yet not completely crush it. (The cucumber will become a beautiful translucent green, in marked contrast to the color of the carrot.) Return the vegetables to the bowl and fluff them up to release them from their cramped state. Set aside.
4, Trim any excess fat from the pork chop. Fill a small saucepan half full with water, add the remaining 1 teaspoon salt, and bring to a rolling boil over high heat. Drop in the chicken breast and pork chop. When the water starts bubbling at the edges of the pan, remove the pan from the heat and cover tightly. Let stand for 20 minutes. The pork and chicken should be firm yet still yield a bit to the touch. Remove them from the pan. Reserve the light stock for another use or discard. When the pork and chicken are cool enough to handle, cut the pork into matchsticks, and shred the chicken with your fingers into thin pieces, pulling the meat along its natural grain. Let the pork and chicken continue to cool to room temperature and then add them to the vegetables.
5, Place the shrimp in a colander and rinse with cold running water, then press gently to drain well. Add the shrimp to the bowl of vegetables and meat.
6, Just before serving, add the peanuts and sesame seeds to the salad and toss to distribute evenly. Pour on the dressing and toss again. (If you don’t want to bite into a piece of chile unexpectedly, strain the dressing over the salad.) Taste and adjust the flavors to your liking, balancing the sour, sweet, salty, and spicy. Transfer to a serving plate, leaving any unabsorbed dressing behind, and serve.
You may ready the vegetables, pork and chicken, and shrimp a day in advance. Keep them in separate covered containers in the refrigerator, and return them to room temperature before tossing Vietnamese salad. The dressing may be prepared several hours in advance.
For a lighter salad, omit the pork and/ or chicken and double the amount of shrimp. Or, you may eliminate the shrimp and add more pork or chicken. Whatever you decide, include at least one of these elements, as they lend richness to the salad.