Preheat oven to 425°F. Toss sweet potatoes with 2 teaspoons oil, ¾ teaspoon allspice, ½ teaspoon cumin and ⅛ teaspoon salt on a large rimmed baking sheet. Roast until browned and tender, about 20 minutes.
Meanwhile, whisk 3 tablespoons lime juice, 2 tablespoons orange juice, 1 teaspoon honey, the grated garlic and the remaining ¼ cup oil and 1 teaspoon salt in a large bowl. Add rinsed black beans, chopped bell pepper, ½ cup each onion, cilantro and peanuts, and the sliced jalapeño (if using); toss to coat.
When ready to serve, add the roasted sweet potatoes and chopped romaine to the bean mixture; toss to coat.
