Use a knife to cut on either side of the large rib running up each collard green leaf. Remove it and discard it. You don't need to go all the way up the leaf, just remove the thickest part. For smaller leaves, just remove the stem. Stack about 4 to 5 leaves, roll them up, and cut into 1/2-inch strips. Repeat with remaining leaves.
Cook bacon in a large pot over medium heat until crisp. Remove with a slotted spoon to a paper towel lined plate.
Add onion to bacon fat and cook over medium heat, stirring occasionally, until softened.
Add broth, vinegar, sugar, red pepper flakes, and tabasco sauce to pot. Stir to combine.
Add collard greens and use tongs to turn and mix them until they reduce in size some. Cover, turn heat to low and cook for 1 hour, stirring occasionally.
Before serving, sprinkle bacon on top and season to taste with salt and pepper.