Preparation

To make the dressing

• With a mortar and pestle, pound the garlic to a paste. Add the cilantro stems and coriander seeds and incorporate them into the paste. Add the sugar and salt; continue pounding. Mix in the fish sauce and lime juice. Add the chiles and pound them lightly until they’re crushed but still remain whole. Taste the sauce—it should be intense, with salty, sour, and peppery tastes predominating and a sweet undertone.

To grill the steak

• Soak the flank steak in the pineapple juice for at least 1 hour (but no more than 3 hours) and light a hot grill fire. Remove the meat from the juice, reserving the juice for basting, and smear the meat with vegetable oil. Grill the steak, over the hottest part of the flame, searing the meat for 5 minutes on each side and basting occasionally. Remove and set aside to rest until cool enough to handle.

To assemble the salad

• Slice the steak across the grain, cutting very thin, bite-size slices. Transfer to a bowl and add the minced lemongrass, lime leaves or zest, and the dressing, garnishing with the crushed chiles from the dressing. Mix well and set aside for 5 or 10 minutes to let the flavors marry. In another bowl, gently toss together the onion, cucumber, romaine, and arugula. Just before serving, add the cherry tomato halves, mint, and cilantro to the vegetables and greens. Toss gently. Add the meat mixture, toss gently, and serve the salad with the warm rice.