1. In a large pot, heat the oil over moderately low heat. Add the scallion bulbs and garlic and cook, stirring occasionally, for 2 minutes.
2. Add the Swiss chard, black-eyed peas, water, broth, Tabasco, and salt to the pot. Bring to a boil. Reduce the heat and simmer, partially covered, stirring occasionally, until the black-eyed peas are tender, about 20 minutes.
3. Stir the ham into the soup and cook until the ham is warmed through, about 2 minutes. Remove the pot from the heat and stir in the pepper, vinegar, and scallion tops.
Variations: Instead of the Swiss chard, use your own favorite greens. Collard, mustard, kale, or beet greens would each lend its unique flavor to the soup.
Wine Recommendation: This soup has more than enough oomph to partner a rich California Syrah. Spicy blackberry and green-olive flavors, a strong earthy streak, and solid structure are its hallmarks, and all of these will go well here.