Cook bacon on medium heat in a large saucepan until lightly browned and fat is rendered. Use a slotted spoon to remove bacon from the pan. Set on a plate lined with a paper towel.
Add the chopped onion to the pot, cook in the bacon fat on medium heat until soft. Add the minced garlic and cook a minute more. Add the chopped peeled potatoes and cook a few minutes more.
Add the tomatoes and chicken broth. Cook until potatoes are cooked through, about 20 minutes (or longer).
Stir in the brown sugar. Add half of the beans to the mixture. Use an immersion blender to blend about half of the soup mixture (or blend half of the soup in a standing blender and return to the pot).
Add bacon to the soup and the rest of the beans. Add salt and pepper to taste.