Grate the onion into a large bowl using a box grater (see video). Add panko, mix briefly to coat in the onion juices.

Grate zucchini and carrot into the bowl. Add remaining Rissoles ingredients. Mix well. Scoop up about 1/4 cup of mixture, form a 1.7cm / 2/3" thick pattie. Indent the middle slightly (Note 2, see photos in post). Repeat with remaining mixture - you should make 10 - 12.

Heat oil in a skillet over medium heat. Add half the patties and cook for 4 minutes or until dark golden. Press LIGHTLY with spatula, if you press hard, you'll press the juices out!

Flip and cook the other side for 3 - 4 minutes until golden.

Transfer to plate, repeat with remaining rissoles.

Serve with tomato ketchup!