- Place bacon in a large skillet and cook over medium-high heat until evenly browned, about 10 minutes. Transfer bacon slices to paper towels to drain.
- Cook and stir onion and 2 pinches black pepper in hot bacon drippings until translucent, 4 to 6 minutes.
- Stir garlic into onion mixture; cook and stir until onion begins to brown along the edges, 4 to 6 minutes. Add 1 tablespoon parsley to garlic and onion; cook and stir until parsley begins to wilt, 1 minute.
- Pour green beans, yellow beans, and 1 1/2 tablespoons parsley into onion mixture; gently turn beans to coat with bacon drippings. Reduce heat to low, partially cover skillet, and simmer until beans are heated through, 5 to 10 minutes.
- Season beans with salt and black pepper to taste, partially cover the skillet and continue simmering, turning occasionally, until beans are hot, 20 minutes. Garnish with bacon and remaining 1 tablespoon parsley.