Peel and grate carrot. Deseed and finely chop ("finely" important!) bell pepper. Chop baby spinach. Add to a big bowl.
Drain tuna in a colander, then put in a bowl and flake with a fork so there is no big pieces left. Add to big bowl.
Add puffed Amaranth and spices, 2 eggs, 1 Tbsp flour and mix very well together.
Preheat a cast iron pan over medium-low heat (NO oil yet).
Try and form a patty. If it doesn't form easily, add a little more flour. 1 Tbsp at a time until patties form easily. (Amount of flour will depend on wetness of tuna and carrots).
Add a good splash of oil to the pan and wait for it to be really really hot. Then carefully add patties.
Fry patties for about 3-5 minutes on one side, then flip carefully and fry another 3-5 minutes on the other side until golden.