Start by bringing a large pot of salted water to a boil over high heat. Add the green beans and blanch them for 5-7 minutes until they are bright green and tender-crisp. This step helps preserve their colour and texture.

While the beans are blanching, prepare a large bowl of ice water. Once the beans have finished cooking, immediately transfer them to the ice water to halt the cooking process and retain their vibrant colour. Drain thoroughly and set aside.

In a large skillet, heat 3 tablespoons of olive oil over medium heat. Add the finely chopped onion and cook for about 5 minutes, stirring frequently until the onion becomes soft and translucent.

Add the minced garlic to the skillet with the onion. Sauté for another 1-2 minutes until the garlic is fragrant, taking care not to let it brown, as this can make it bitter.

Add the diced jamón serrano to the skillet. Sauté for 3-4 minutes, stirring occasionally. The jamón should start to release its flavours and become slightly crispy, enhancing the savoury profile of the dish.

Add the blanched green beans to the skillet with the onion, garlic, and jamón. Toss gently to combine, allowing the flavours to meld. Continue cooking for another 5-7 minutes, stirring occasionally to ensure even heating.

Season the mixture with salt and freshly ground black pepper to taste. Remember that jamón is already quite salty, so taste before adding more salt. Stir well to evenly distribute the seasoning.

Serve the Judías Verdes con Jamón warm, either directly from the skillet or transferred to a serving dish. Garnish with a sprinkle of freshly ground pepper for a touch of flavour and contrast. This dish pairs wonderfully with rustic bread to enjoy every savoury bite.