Put a large soup pot on the stove over medium heat.

Add the olive oil to the pot and let it warm for about 30 seconds.

Add the diced onion to the pot. Cook for 4 minutes, stirring a few times, until it starts to soften.

Add the sweet potatoes to the pot. Cook for 5 minutes, stirring now and then, until the edges look slightly glossy.

Add the minced ginger and garlic to the pot. Stir for 1 minute, just until fragrant.

Add the curry powder, 1 teaspoon of salt, and 1/2 teaspoon of black pepper to the pot. Stir for 30 seconds so the spices warm in the oil.

Add the tomato paste to the pot. Stir for 1 minute, until it darkens a little and coats the vegetables.

Pour the chicken broth into the pot. Stir and scrape the bottom of the pot with a wooden spoon to loosen any stuck bits.

Raise the heat to high and bring the broth to a boil.

Lower the heat so the soup stays at a gentle simmer. Cook for 12 to 15 minutes, until the sweet potatoes are tender enough to pierce easily with a fork.

Put the peanut butter in a medium bowl. Ladle about 1 cup of the hot broth from the pot into the bowl.

Whisk the peanut butter and hot broth together until the mixture is smooth and pourable, with no thick lumps left.