Brush a grill or grill pan with the oil and heat over medium-high. In a medium bowl, whisk 2 1/2 tsp. sriracha and 1 tsp. sugar; season. Add the shrimp and toss to coat. Grill just until opaque in the center, about 2 1/2 minutes per side; transfer the shrimp to a plate.
In a small bowl, whisk the remaining 1 1/2 tsp. sriracha and 3 tsp. sugar with the fish sauce, lime juice, vinegar and 3 tbsp. water until the sugar dissolves. In four 24-oz. jars, layer the spinach, noodles, cucumber, shrimp, scallions, chile, peanuts and mint. Drizzle with the dressing and serve with lime wedges for squeezing on top.