Winter Vegetable Stew

Ingredients
1 can (28 oz) Italian-style peeled whole tomatoes
4 medium red potatoes; cut into 1/2 inch pieces
4 medium stalks of celery, cut into 1/2 inch pieces
3 medium carrots, cut into 1/2 inch pieces
2 medium leeks, cut into 1/2 inch pieces
1 can (14 oz)  vegetable broth
1/2 tsp salt
1/2 tsp. dried thyme leaves
1/2 tsp. dried rosemary leaves
3 T. cornstarch
3 T. cold water

Directions
Drain tomatoes, reserving liquid.  Cut up tomatoes.  In 4-5 quart slow cooker, mix tomatoes, tomato liquid and remaining ingredients except cornstarch and water.
Cover; cook on Low heat setting 8- 10 hours.
In a small bowl, mix cornstarch and water; gradually stir into stew until blended.  Increase heat setting to High.  Cover; cook about 20 minutes, stirring occasionally until thickened.