Sprinkle the striploin steaks with spices, season with salt and pepper, then rub with half the olive oil. Set aside.
Sauté the onion, celery, garlic and bay leaves in a medium saucepan over a moderate heat in the remaining olive oil for 5 minutes, until softened. Add the butter, sprinkle with flour, then pour in the sherry and stock. Simmer until thickened, then fold in the beans and herbs.
Cook the striploin steaks over a hot barbecue grill for 8 minutes, turning often, until medium. Allow to rest for 2 minutes, then carve and serve with the white bean casserole.