To make the bean lettuce cups, cook the beans a day in advance for best results. Sort through the beans and remove any stones. Rinse the beans, place in a saucepan and add 3 cups water. Bring to a boil and boil for 5 minutes. Remove from the heat, cover the pan and let stand for 1 hour. 

Drain the beans and add 3 cups fresh water. Bring to a boil, then reduce the heat and simmer until the beans are half tender. Add a generous pinch of salt along with the onion, carrot, olive oil and bay leaf. Continue cooking until the beans are tender. Adjust the seasoning with salt. Let the beans cool in their liquid. 

About 1 hour before serving, drain the beans, transfer to a bowl and toss with a couple of healthy glugs of extra-virgin olive oil. Adjust the seasoning with salt and white pepper. 

Remove the outer leaves from the butter lettuce and place a small scoop of beans inside each leaf.

To make the roasted beef sirloin, preheat the oven to 450°F. 

Rub the meat with the 3 tablespoons salt and the crushed black peppercorns. In a large ovenproof fry pan over medium-high heat, warm the olive oil. When the oil is hot and shimmering, sear the meat well on both sides, then transfer the pan to the oven. Roast for 4 minutes, flip the meat over and roast for 2 minutes more. 

Meanwhile, in a mortar, combine the oregano, parsley, garlic, vinegar, extra-virgin olive oil, lime zest and lime juice and pound with a pestle until homogenous (the mixture should be rustic in texture). Season with salt and black pepper.

Transfer the meat to a rack set over a plate or baking sheet and let rest until cool. Cut the beef into slices. Serve with the oregano-parsley sauce and the bean lettuce cups.