Soak dried pineapple in a bowl of water until softened, at least 30 minutes; drain.
Heat oil in a large pot over medium heat. Cook and stir sweet onion, celery, and leek in hot oil until tender, about 4 minutes.
Sprinkle curry powder, cumin, cayenne pepper, and salt over the vegetables; stir to coat. Cook and stir until strongly fragrant, about 4 minutes more.
Add peanut butter to the pot. Drain about half the juice from the tomatoes and discard; pour remaining tomatoes and juice into the pot. Cook until the tomatoes soften, about 5 minutes. Pour 3 cups water into the pot; add drained pineapple.
Bring the mixture to a boil, reduce heat to medium-low, and simmer soup for 1 hour. Stir cream, green onion, and garlic into the soup.