In blender, purée herbs, oil, vinegar, shallot, salt, pepper and hot pepper flakes (if using) until smooth.
Salad
Cook barley according to package instructions. Drain and rinse with cold water until cool.
Preheat barbecue to medium-high heat; grease grill. Brush corn with oil, then cook, turning occasionally, until slightly charred, 8 to 10 minutes. Transfer to cutting board; let cool enough to handle. Break in half, then cut kernels from cob.
To serve, arrange tomatoes, peaches, barley and corn on platter. Drizzle dressing overtop.
Notes
Hulled barley is a whole grain that is minimally processed, more nutritious than pearl barley and distinguishable by its slightly darker colour.