Preheat the broiler. Combine the lima beans and 1 cup water in a medium saucepan over medium heat; bring to a simmer, then cover and cook until almost tender, about 7 minutes. Add the peas, 1/4 teaspoon salt, and pepper to taste; cover and cook until the peas and beans are tender, about 5 more minutes. Drain and return to the pan. Add 1 tablespoon butter and the parsley; stir to coat. Meanwhile, put the salmon skin-side down on a baking sheet lined with foil; season lightly with salt and pepper. Broil until browned on top, 6 to 8 minutes. Heat the remaining 1 tablespoon butter in another saucepan over medium heat; add the shallot and cook until translucent, about 2 minutes. Add the vinegar and boil until reduced by half, about 2 more minutes. Stir in the tomato paste, then add the heavy cream and 3/4 cup water and simmer until thickened, about 2 minutes; stir in the herbs. Drizzle over the salmon and serve with the bean mixture.