For the vegetables, peel the carrots then halve lengthwise and cut at an angle into long pieces. Finely dice the onion and chop the parsley.
Heat the butter in a pot and braise the onions until translucent. Add the carrots and braise briefly, then add half of the parsley, a little salt, and water, cover, and simmer on medium heat for 8-10 minutes.
Brown the cut-up pieces of sausage in a heated pan with oil. Add the onion slices and brown them as well. Prior to serving, season the mixture with salt, pepper, and a few drops of Maggi seasoning sauce.
Arrange carrots alongside the bratwurst on serving plate and garnish with the remaining parsley. Top with curry ketchup as desired.