In a small saucepan, bring 2 cups of water and 1/4 teaspoon salt to a boil. Add the barley, cover, and simmer until just tender, about 40 minutes. Add the edamame beans, stir, and cover; continue cooking until barley is tender and edamame is bright green, about 5 minutes more. Remove from heat and fluff barley with a fork.
Heat 1 tablespoon oil in a large skillet over medium heat. Cook ginger and garlic until fragrant, about 1 minute. Add the brussels sprouts and cook, stirring, until bright green and tender, about 2 minutes.
Add remaining tablespoon oil to the pan. Add the spinach and cashews to the pan, and cook until the spinach has wilted, about 2 minutes, stirring constantly. Stir in barley and edamame. Season to taste with salt and crushed red pepper.