The best Schnell-Imbisse (fast-food stalls) make their own currywurst sauce, essentially a curry powder-flavored ketchup.
- 1 large yellow onion, finely chopped
- 2 Tbsp. canola oil
- 2 Tbsp. curry powder
- 1 Tbsp. hot paprika
- 2 cups whole peeled canned tomatoes (with juice), crushed by hand
- 1⁄2 cup sugar
- 1⁄4 cup red wine vinegar
- Kosher salt
- Heat oil in a saucepan over medium heat. Add onion and cook until soft, 8–10 minutes. Add curry powder and paprika; cook for 1 minute more. Add tomatoes, with their juice, sugar and vinegar; stir to combine. Season, increase heat to high and bring to a boil. Reduce heat to medium-low and simmer, stirring occasionally, until thickened (about 25 minutes). Purée sauce in a blender until smooth. Strain through a sieve. Serve hot over sausage.