Bring a large pot of water to a boil. Blanch the green beans for 2 minutes, drain and keep aside. If using thinner beans like haricot verts, blanch for 1 minute.
Heat oil in a large skillet over medium low heat. Add garlic and cook until translucent. 2 minutes.
Add the red curry paste and mix and cook until fragrant . 1 minute.
Add the soy sauce, lemon, lime leaves or zest, water, sugar, cayenne and salt and mix well. Increase heat to medium. Cook for a minute.
Add the green beans. toss to coat. Cover and cook for 3 to 6 minutes or until tender to preference.
Taste and adjust salt, sweet, and spice. I added some red pepper flakes as the curry paste I use is not hot. Serve hot with rice or noodles or cooked grains of choice. The beans can also be garnished with crushed peanuts or almonds and cilantro.
Notes
To make this a meal, add some crisped or baked tofu when you add the beans.