Yummy Ham and Potato Soup

I found this on All Recipes, Recipe Spinner... I added a few steps to make it a bit thicker.

Ingredients
8 ounces cubed cooked ham
1 cup chopped onion
1 tablespoon butter
2 1/2 pounds potatoes, peeled and diced
2 (14.5 ounce) cans chicken broth
1 tablespoon prepared Dijon-style mustard
1 1/2 cups milk
1 (10.75 ounce) can condensed cream of celery soup
1/4 teaspoon garlic powder
1/4 black pepper

Directions
1. In a large saucepan over medium-high heat, sauté ham and onions in the butter, until the onions are translucent. Stir in the mustard, add a few tbsp of flour to create a rue. Let cook for a few minutes, be careful not to let it burn. Then whisk in the chicken broth. Add potatoes, bring to a boil and cook until potatoes are tender.

2. Combine the milk and cream of celery soup; stir in to the saucepan. Season with garlic powder and pepper. Heat through, but do not boil. Serve hot.