Creamy Barley and Tomato

2 tablespoons olive oil
1 large onion, chopped
2 cups pearled barley
28 ounces diced tomatoes (look for Eden or Jovial brand glass jar)
1 cup dry white wine
2 1/2 cups water
8 cups baby spinach
1/2 cup freshly grated imported Grana Padano parmigiano cheese
fresh parsley, finely chopped
Celtic sea salt and freshly-ground black pepper

Coat the bottom of large saucepan with olive oil and place it over medium heat. Add the onion, season with Celtic salt and pepper, and sauté until the onion softens, about 7 minutes.  Add the barley, tomatoes, wine and water and bring to a boil.  Reduce heat to low and simmer until the barley is tender, about 15 minutes. 

Add the spinach and cheese and cook until the spinach wilts and the cheese is melted. Season to taste and garnish with additional grated cheese and parsley.