Bring a large pot of water to a boil and add green beans, once bright green and tender after 2-3 minutes, add to a cold ice bath so they stop cooking.
Meanwhile, in a skillet over medium heat, add bacon pieces and cook until crispy. Remove bacon bits and set aside.
Reserve 2 Tbsp of rendered bacon fat and add to a small mixing bowl (and optionally save all of it for yourself).
Lightly clean the skillet and add olive oil over medium heat, add onions and sauté until soft (3-4 mins).
Add steamed green beans to onions and mix well, remove from heat. Add green beans, onions, and bacon bits to a serving bowl.
Meanwhile in a small mixing bowl, add bacon at, vinegar, mustard, honey and a pinch of sea salt. Whisk vigorously until a thick, creamy dressing forms. Pour dressing over the green beans dish and toss well to coat, serve!