Heat oil in a 10-inch heavy skillet over moderately high heat until hot but not smoking, then sauté almonds, stirring constantly, until golden, about 4 minutes.
Transfer almonds with a slotted spoon to a blender.
Add bread cubes, parsley, garlic, and saffron to oil in skillet and cook over moderate heat, stirring constantly, until golden, about 2 minutes.
Transfer about one fourth of crouton mixture to a small bowl for garnish, then transfer remainder to blender.
Add broth to blender and purée mixture until smooth.
Transfer purée to a 2- to 3-quart heavy saucepan and stir in water. Simmer, uncovered, stirring occasionally, until slightly thickened, about 5 minutes. Stir in salt and vinegar and serve soup topped with croutons.