Heat a heavy skillet on medium heat (don't use a nonstick pan). Once it's heated, add the ground chicken and stir periodically with a wooden spoon to break it up into chunks.
1 pound ground chicken
While the chicken is cooking, thinly slice the green onion and shallot. Mince the lemongrass. Slice your chili in half and remove the seeds and ribs. Then slice it as thinly as you can. While you're prepping your veggies, periodically return to the stove to stir and break up the cooking chicken.
Once the chicken is no longer pink, add the chicken stock and turn the heat up slightly. You'll want to evaporate the liquid and intensify the flavor. Add the veggies you just chopped and stir.
1/4 cup chicken stock
While the veggies cook down a few minutes, prepare the "dressing" for the salad. Juice your limes. Add them to the fish sauce, sugar, and Thai chili paste. Add this mixture to your chicken and stir to combine.
2 limes, 1/4 cup fish sauce, 2 teaspoons sugar, 2 teaspoons Thai chili paste
Dry toast the uncooked rice over medium heat in a heavy saucepan. Shake the pan every thirty seconds or so to keep the rice from burning. After two to three minutes, you'll start to notice the grains are turning slightly brown and are smelling a little nutty. Remove from the heat and grind in a spice grinder. Stir into the larb.
2 teaspoons rice
Remove the chicken from the heat and let cool slightly. While you're letting this cool, rough chop the mint and cilantro. Stir them in just before serving to help keep them from wilting too much.
1/3 cup mint leaves, 1/2 cup cilantro
To serve, wash your Boston lettuce and carefully separate the leaves. Use each leaf like a cup and spoon some of the larb mixture into it. Roll and eat.