It's easy to vary this recipe: Use firm tofu or chicken instead of fish.
Make the salad: Heat oil in a large saute pan over medium-high heat. Add mushrooms, and cook, stirring occasionally, until browned and crisp, about 8 minutes. Reduce heat to medium, add shallots and garlic, and cook until tender, about 3 minutes. Add edamame, and cook, stirring occasionally, for about 3 minutes. Add barley, and heat through, about 2 minutes. Sprinkle with salt, and season with pepper.
Make the fish: Sprinkle both sides of tilapia with salt, and season with pepper. Heat oil in saute pan over medium-high heat. Add tilapia, and cook until browned and crisp, about 3 minutes per side. Add lime juice and 1/4 cup water, carefully swirling pan to combine. Serve tilapia with barley salad, and drizzle with sauce.