Bring a large pot of well-salted water to a boil. Fill a large bowl with ice and cold water. When the water in the pot is boiling, add the green beans all at once and cook for 1 to 2 minutes, until bright green and crisp-tender. Immediately drain the beans and submerge in the ice bath.
Heat a large skillet over medium heat. Add the almonds and toast, stirring constantly, until fragrant and starting to turn golden, about 4 minutes. Sprinkle with a pinch of salt and transfer to a bowl.
Add the butter to the skillet over medium heat. Add the garlic, then add the green beans and ½ tsp. salt, and cook while stirring. Cook until the garlic is fragrant and the green beans are tender, about 1 minute. Add the lemon zest.
Transfer to a platter and top with the almonds. Serve warm or at room temperature.
Store in an airtight container in the fridge for 3 days, or in the freezer for 3 months. Reheat in a 350F oven.