In a medium saucepan, combine the black-eyed peas and water. Bring to a boil over high heat, then reduce the heat to low and simmer, covered, for about 30 minutes, until the peas are tender but not mushy. Discard any liquid remaining in the pan and transfer the peas to a large bowl.
Coat a large nonstick skillet with cooking spray and place over medium-high heat. Add the onion, pepper and squash and cook, stirring occasionally, for 5 minutes. Turn the heat to low, cover the pan and continue cooking until the squash is just tender, 5-7 minutes more. Stir in the walnuts.
Add the walnut mixture to the peas along with the vinegar and parsley. Stir and toss to combine, then season with salt and pepper to taste. Let cool slightly.
Spoon about 1/4 cup of the black-eyed pea and walnut mixture into each lettuce leaf. Fold the leaves in half and eat the wraps "taco-style."
Per serving: 262 calories, 11 g protein, 11 g total fat, 1 g saturated fat, 0 mg cholesterol, 34 g carbohydrate, 9 g dietary fibre, 15 mg sodium