Season your water with salt. Add your cavolo nero and blanch for 3 minutes. Drain, squeeze, cool and chop relatively fine. Pop in a large mixing bowl. To the chopped cabbage, add the herbs, cheese, pepper, nuts, herbs, cumin and the two beaten eggs. Check for seasoning- it should be about right if your cabbage water was salty enough (the feta is quite salty).
Lay out a sheet of filo. Brush with oil then lay another sheet on top (move quite quickly here). Repeat until you have 4 sheets in an oiled pile. Brush the top half of the top sheet with oil. Along the bottom, lay your cavolo mix in a ‘log’ along the width of the filo sheet. Roll the filo over the mix and into a long, fat cigar. Wind this into a large, oiled skillet. Repeat until you have 3 or 4 snakes in a spiral and the dish is full. It’s a good idea to cover the dish with brush with egg and sprinkle with sesame seeds/onion seed. Bake for 40 minutes at 180°C or until the filo is crisp and brown and the filling hot. Dig in!