Cook barley according to package directions, or in plenty of lightly salted boiling water for about 35 to 45 minutes until it is plump and tender, and still slightly chewy. Drain and cool.
Tenderize kale by blanching it in boiling water for 2 to 3 seconds or cooking in the microwave for 1 minute. Rinse in cold water to stop cooking, and squeeze dry. Fluff and uncrimp dry kale pieces with your fingers.
In a medium bowl, mix together barley, kale, grapes, salmon and walnuts.
To prepare dressing: In small bowl, whisk together lemon juice, garlic, salt, pepper and cayenne. Gradually mix in olive oil.
Pour onto salad and fold gently to combine. Serve immediately or refrigerate.