Chop the onion finely. Mince the garlic cloves. Cut the beans in half.

Heat the olive oil in a large saucepan over medium heat. Stir in the onion and 1 tsp sea salt. Cook, stirring often, until the onion softens, about 5 minutes. Stir in the minced garlic, the Pimentón de la Vera and the black pepper. Cook, stirring until fragant, about 1 minute.

Stir in the crushed tomatoes (if using canned tomatoes, add 1/2 cup water) . Bring to a simmer over medium-high. Stir in the green beans and return to a simmer. Cover and cook, stirring occasionally, until the beans are tender, about 40 minutes (the beans must stay very moist in the bubbling sauce, so add some more water if needed).

Stir in the lemon juice and adjust for salt. Serve warm with a slice of crusty bread.