Add the barley and water (or stock) to a medium saucepan.

Cover the saucepan.

Simmer over low heat for approximately 1 hour, or until the barley is cooked.

Heat a nonstick pan over medium heat.

Add both vegetable oil and dark sesame oil to the pan.

Saute the diced onions, stirring occasionally, until they turn brown (about 5-7 minutes).

Add the minced garlic and sliced shiitake and button mushrooms to the pan.

Saute for approximately 3 minutes, or until the mushrooms are softened.

Add the spinach leaves, cooked barley, and sesame seeds to the pan.

Saute for 5 minutes, or until the barley is heated through and the spinach has wilted.

Season with tamari soy sauce and cayenne pepper to taste.

Serve hot.