Step 1In the morning, put the water and the lamb shank into an earthenware pot-au-feu or a large heavy pot. Slowly bring to a boil while skimming off the gray scum from the surface.
Step 2When it comes to a boil add the salt, cayenne, squash, fresh borlotti and white beans (or the soaked and boiled dried beans), onion, leeks, carrots, garlic, potatoes and tomatoes.
Step 3Return to a boil and adjust the heat to maintain a simmer or light boil, lid ajar, for about 30 minutes. Add the runner or string beans, zucchini and pasta and cook an additional 15 to 20 minutes. (If making ahead do not add the pasta now. When ready to serve, reheat the soup adding the pasta and cook according to package instructions.) Cool, uncovered.
Step 4Remove the lamb shank, separate the flesh from the bone, cut the flesh into small pieces and add the pieces to the soup. If the soup seems too thick (it should be thick), add a bit of boiling water and taste for salt.
Step 1While the soup is cooking, prepare the pistou. In a large marble mortar, pound the coarse salt, pepper, garlic and basil to a liquid paste with a wooden pestle. Add the tomato and crush, pound, and stir until well mixed, then stir in the olive oil, adding it slowly. (Makes three-fourths cup).
Step 2Remove the soup pot from the heat and stir the pistou into the soup (wash out the mortar with a ladle of soup and pour it back into the pot). The pistou can also be spooned individually into each soup bowl. Lulu pours the soup into a heated, giant antique soup tureen and serves it at the table accompanied by the grated cheeses.