Cook the rice noodles as the label directs; drain and rinse under cold water to cool, then snip into smaller pieces with kitchen shears. Meanwhile, make the dressing: Whisk 1/4 cup fish sauce, the juice of 1 lime, 2 tablespoons vegetable oil, the jalapeno, sugar, half of the garlic and 1/2 cup water in a small bowl; set aside. Preheat a grill or grill pan to medium high. Combine the zest and juice of the remaining lime and the remaining garlic, 1 tablespoon vegetable oil and 2 teaspoons fish sauce in a medium bowl. Add the shrimp and toss to coat. Grill the shrimp until lightly charred and opaque, about 2 minutes per side. Toss the noodles, romaine, carrots, herbs and bean sprouts in a large bowl. Gradually add enough of the dressing to coat; toss. Divide among bowls and top with the shrimp. Drizzle with the dressing.