Place peas in large saucepan. Add enough water to cover by 3 inches. Let peas soak 2 hours. Drain peas; return to same pan. Add 4 cups water, onion, bay leaf, and salt. Bring to boil; reduce heat to medium, cover partially, and simmer until peas are tender, about 30 minutes. Discard onion and bay leaf. Drain. Transfer peas to rimmed baking sheet to cool. (Can be prepared 1 day ahead. Cover and refrigerate.)
Preheat oven to 400°F. Arrange pumpkin in single layer in 8x8x2-inch glass baking dish. Drizzle with 3 tablespoons water and oil. Sprinkle with salt and pepper. Bake until tender when pierced, turning occasionally, about 15 minutes. Add garlic; stir to coat. Cool.
Whisk oil and lime juice in bowl. Season dressing with salt and pepper. Combine all remaining ingredients and peas in large bowl. Add dressing; toss. Season with salt and pepper. Add pumpkin; toss. (Can be made 2 hours ahead. Let stand at room temperature.)