Wash the green beans and trim off the ends, place to one side.
Fill a medium pan with water, sprinkle in a little salt, and place on a high heat on the stovetop and bring to a boil.
Fill a large bowl with cold water and add in some ice cubes.
Once the water in the pot is boiling, add in the trimmed beans. Cook for 2 to 3 minutes til fork tender, but still with a bite.
Drain the beans and place them immediately in the bowl of iced water. Leave to one side.
Place a skillet on a medium heat on the stovetop and add in the oil. Once hot, add in the diced garlic. Cook for 2 to 3 minutes, stirring occasionally til softened.
Add the butter and balsamic to the skillet. Allow the melted mixture to simmer for a minute, but don't let it fully reduce.
Add the cooked green beans to the skillet and toss in the balsamic sauce.
Serve the green beans, and spoon over some of the balsamic and garlic from the skillet.