Roasted Cauliflower Larb

Name: Roasted Cauliflower Larb
Ingredients: 1 large head of cauliflower, cut into large florets with some stalk attached; 3 tablespoons olive oil; 3 green Thai chiles, finely chopped; 1 (3-inch) piece lemongrass, tough outer layers removed, finely chopped; 4 makrut lime leaves, finely chopped; 1/4 cup fish sauce; 1/4 cup fresh lime juice; 1/4 cup glutinous (sticky) rice; 5 scallions, thinly sliced; 2 cups chopped pea shoots (tendrils); 1 cup chopped cilantro; 1 cup chopped mint; Kosher salt; Sliced Persian cucumber and Bibb lettuce leaves (for serving); A spice mill