Cook the bacon in a heavy stock pot or Dutch oven until done. Remove bacon from the pot and drain out most of the bacon grease. Leave about a 1/4 cup on the bottom. Use the grease to saute celery and onion until they turn clear. Add garlic and cook for another 2 minutes. Add the potato and mix into the vegetable mixture. Cover and simmer until potatoes are cooked.
Mix the flour and butter together with a fork. Add the mixture into a new pan and melt over medium heat. Whisk constantly for 1 to 2 minutes until it melts. Whisk in the heavy cream and cilantro. Bring mixture to a boil, stirring constantly, until thickened. Add the mixture to your potato mixture. Puree about 1/4 of the soup or as creamy as you like. Season to taste.