Heat 2 large skillets and add 1 tablespoon of olive oil to each. Add half of the mushrooms to each skillet, season with salt and pepper and cook over moderately high heat, stirring, until browned, about 3 minutes. Add the remaining 2 tablespoons of olive oil to the skillets. Add the garlic and shallots to the skillets and cook over moderate heat, stirring, until fragrant, about 2 minutes; stir in the chopped ham, olives and crushed red pepper, then stir in the <em>fideos</em>. Add the sherry to the skillets and cook over moderately high heat until reduced by three-quarters, about 2 minutes. Stir in the ham hock broth and the lemon juice, then add 1 cup of hot water to each skillet. Season with salt and pepper and bring to a simmer.