How to Make It
In a large pot, melt the butter. Add the fennel, onion and garlic and season with salt. Cook over moderate heat, stirring, until the vegetables are tender but not browned, 8 to 10 minutes. Add the milk and simmer for 15 minutes. Add the peas and simmer until tender, 7 to 8 minutes.
Working in batches, puree the soup in a blender. Strain it through a fine sieve set over a large bowl. Season with salt.
In a small bowl, combine the ham with the shallot, chives, olive oil and sherry vinegar. Spoon the ham salad into the center of 4 bowls. Ladle the warm soup into the bowls, garnish with the pea tendrils and serve immediately.