In this video, you’ll see how to make homemade ketchup in your slow cooker. This is ketchup with bright tomato flavor and no high-fructose corn syrup. Canned crushed tomatoes are sweetened with sugar and spiced up with vinegar and seasonings, then cooked down in the slow cooker to a tasty paste. After many hours in the slow cooker, you’ll finish the sauce by blending it with an immersion blender and running it through a fine strainer. Easy! Watch the video, then get the recipe for Chef John's Homemade Ketchup. Now see how to make Chef John's Cottage Fries.