Heat 2 tablespoons of olive oil on a medium-sized saucepan over medium-high heat.
Once the oil is ready, add the chopped onions.
Cook until they turn soft, then add the brown sugar, cinnamon powder, curry powder, salt, dried chili pepper, and tomato paste.
Adjust the heat to medium-low and cook everything for about 3 to 5 minutes, stirring often.
Pour pineapple juice and vinegar.
Mix and cook for about 2 minutes.
Add the crushed tomatoes.
Turn the heat up to medium and cover the saucepan with a lid.
Bring to a boil, then adjust heat to medium-low and simmer for 40 to 45 minutes.
Taste and adjust the seasoning, mix, then remove it from the heat.
Use an immersion blender to blitz your curry ketchup.
Set your currywurst sauce aside to cool.
Pour the remaining olive oil into a skillet over medium-high heat.
Once the oil is ready, fry the bratwurst, turning on all sides, to make sure they're evenly cooked.
Slice the fried bratwurst into small rounds (no more than 1-inch thick), then serve with the cooled curry ketchup.
Sprinkle with more curry powder and serve with some fries --- enjoy!