In a large Dutch oven or cast iron braiser, cook bacon over medium heat until crisp, about 5-7 minutes. Use a slotted spoon to remove the bacon to a paper towel-lined plate, leaving the drippings in the pot.
Add the onion and cook, stirring, until softened, about 5-6 minutes. Add the green beans, chicken broth, sugar, soy sauce, black pepper, and half of the cooked bacon into the pot with the onion. Set the remaining half of the bacon aside to use as a garnish at the end.
Bring the broth to a boil; reduce the heat to low, cover, and simmer (stirring occasionally) until the green beans are very tender, about 40-45 minutes. Taste and season with salt, if necessary. Garnish with reserved crispy bacon.