In a large skillet, heat butter and olive oil over medium-low heat. Once melted, add sliced red onion. Saute for 8-12 minutes or until soft and caramelized. Add garlic cloves and cook for 1 minute longer.
Meanwhile, heat a large pot of water over high heat. Bring to a boil and add some salt. Add green beans and cook for approximately 2-3 minutes depending on how cooked you like the green beans.
Remove green beans from boiling water and add to skillet. Season with salt and pepper. Continue to cook until the desired doneness.
Pour over platter and top with lemon zest and almonds. Season to taste.