In a 2 qt saucepan, combine the stock, peppers, tomatoes, onions and garlic. Bring to a boil. Simmer over medium heat for 15 minutes.

In a cup, combine the cornstarch and water. Add to the pan. Cook, stirring, until the mixture thickens. Remove from the heat.

Preheat oven to 400 deg F. Coat a 13 x 9 inch baking dish with olive oil cooking spray.

While the sauce is cooking, steam the spinach for 5 minutes, or until wilted. Be sure to squeeze all excess moisture out of the spinach to prevent your enchiladas from becoming soggy. To prepare corn tortillas for filling and rolling, warm briefly in oven or between paper towels in the microwave for about 10 seconds until they are softened and warm. Divide the spinach among the warm tortillas and roll to enclose it. Add tortillas, seam side down, to the baking dish, in a single layer. Top with tomato sauce mixture and bake in oven for 10 minutes. Serve immediately.