Sauté the onion: In a skillet over medium heat, warm olive oil and sauté chopped onion for 3–5 minutes until soft and golden.
Add garlic: Stir in minced garlic and cook for 30 seconds, just until fragrant.
Build the broth: Pour in vegetable broth, brown sugar, soy sauce, salt, and pepper. Stir to combine.
Add green beans: Add canned (drained), frozen, or fresh green beans. Simmer on low for 10–15 minutes until tender.
Finish the flavor: Add red pepper flakes and a splash of vinegar or liquid smoke, if using. Adjust seasoning to taste.
Let it rest: Remove from heat and let sit for 5–10 minutes before serving to deepen the flavor.