Step 1

Heat oil (or ghee) in a large pot over medium-high heat until shimmering. Add onion, celery and salt; stir to coat. Cook, stirring occasionally, until the vegetables are softened and begin to turn golden brown around the edges, about 10 minutes. Stir in tomato paste, sage, white pepper and crushed red pepper, if using. Cook, stirring constantly, until fragrant, about 1 minute. Add stock, increase heat to high and bring to a simmer. Once simmering, add peanut butter, whisking until it melts into the stock. Reduce heat to low and simmer, stirring occasionally, until the soup is slightly thickened, 15 to 20 minutes. Remove from heat.

Step 2

Using an immersion blender or in batches in a blender, process the soup until it is very smooth. (Use caution when blending hot liquids.) Stir in vinegar. Serve the soup topped with chopped peanuts and chives (or parsley).