Grate carrot and mix with all the dry ingredients in a large bowl.
Add quark. Using the kneading attachment of your electric mixer or stand mixer, knead dough till smooth, gradually adding the water.
Grease a 2 lb (900g) loaf tin very well. Tip dough into tin and even out the surface with a wet spatula. Sprinkle generously with oats and sunflower seeds. The dough will be quite sticky.
Place tin in the cold oven. Set oven to 220 C / 200 fan / Gas 7. Bake till the bread is browned and sounds hollow when you tap the bottom, about 50 minutes from the time the oven reaches the set temperature. If the bread gets too dark at the top but isn't fully baked through yet, cover it with a piece of aluminium foil.