Add the trimmed green beans to the boiling water. Boil until they are bright green and just tender-crisp, about 3 to 4 minutes depending on thickness.

Shock in ice bath

While the beans boil, fill a large bowl with 2 cups ice and cold water. When beans reach desired doneness, immediately transfer them with a slotted spoon or drain into a colander and plunge into the ice bath to stop cooking. Let sit 1–2 minutes.

Drain

Drain the blanched beans thoroughly in a colander and pat dry with clean kitchen towels or paper towels. Set aside.

Garlic Sauté

Heat fats

In a large skillet over medium heat, add 2 tablespoons unsalted butter and 1 tablespoon extra-virgin olive oil. Heat until butter is melted and begins to foam but not brown, about 1 minute.

Cook garlic

Add 4 cloves garlic (thinly sliced or minced) to the skillet. Sauté gently, stirring constantly, until fragrant and just starting to turn golden at the edges, about 45–60 seconds. Be careful not to burn the garlic.

Add seasoning

Stir in 1 teaspoon red pepper flakes and season with 1 teaspoon kosher salt and 1 teaspoon freshly ground black pepper. Cook another 10–15 seconds to bloom the spices.

Toss beans

Add the drained blanched green beans to the skillet. Increase heat to medium-high and toss or stir to coat the beans evenly with the garlic butter oil. Sauté 2–3 minutes until heated through and edges begin to blister slightly.

Finish with lemon

Remove the skillet from the heat and squeeze in 1 tablespoon fresh lemon juice. Toss to combine and taste; adjust salt and pepper if needed.

Garnish and serve

Transfer garlic green beans to a serving dish. Sprinkle with 2 tablespoons toasted sliced almonds or chopped parsley if using. Serve immediately.