Wash and dry kale leaves with a kitchen towel. Remove the ribs with kitchen scissors. Roughly chop kale and transfer to a bowl. Sprinkle with 1-2 pinches of salt. Knead kale for a minute until it's soft and dark.
Set a large pan or skillet over medium-high heat. Slice the grapefruit into 1 cm (or ½ inch) thick slices, discarding the rounded bottom and top. Add the olive oil to the pan. Dip the grapefruit slices into Demerara sugar from both sides. Cook for about 2 minutes, then flip them over and cook for 2 more minutes. Remove from the pan and let cool.
Distribute kale on two plates. Slice avocado and add it to kale. Discard the zest from the grapefruit slices and cut them in halves. Transfer to plates. Break feta cheese with your fingers on top of the salad. Sprinkle with sesame seeds.
Combine chopped kale leaves, cashew nuts, grated parmesan, olive oil, tarragon, lime juice, garlic, salt and black pepper for the pesto dressing. Blend with an immersion blender until smooth.