Set a large soup pot or Dutch oven over medium heat.

Add the oil to the pot and heat it for about 30 seconds, until it looks loose and shiny.

Add the bell pepper, broccoli, cabbage, and the white parts of the scallions to the pot.

Cook the vegetables for 4 to 5 minutes, stirring often, until the cabbage starts to soften and the bell pepper looks bright and slightly tender.

Add the garlic to the pot.

Cook for 30 seconds, stirring, until the garlic smells fragrant but has not browned.

Pour the vegetable broth into the pot and raise the heat to high.

Bring the broth to a boil. You should see steady bubbles across the surface.

While the broth comes to a boil, put the peanut butter in a medium bowl.

Ladle about 1/2 cup of the hot broth into the bowl with the peanut butter.

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

Scrape the peanut butter mixture back into the pot and stir well to blend it into the broth.