Preheat oven to 200°C. Drizzle pumpkin with 1 tbsp olive oil, season to taste with salt and freshly ground pepper and roast on a baking paper-lined oven tray, turning occasionally for about 25 minutes until browned on the edges and tender.
Preheat a char-grill to high. Combine about 1 tbsp olive oil with pepper, chilli flakes, ground coriander and a pinch of salt, brush over steaks and set aside at room temperature while you cook the broccoli. Drizzle broccoli slices with 1 tbsp olive oil and char-grill, turning occasionally for about 8 minutes until just tender and charred a bit on the edges, then when cool enough to handle, coarsely chop and set aside. Wipe char-grill clean then cook steaks, turning once, until browned and cooked to your liking (5-6 minutes for medium-rare, 7-8 minutes for medium), transfer to a plate, cover loosely with foil and set aside to rest for 5 minutes, then thickly slice.
Mix the yoghurt-tahini sauce ingredients in a bowl to combine and season to taste with salt and pepper.
While the meat rests, combine the kale, shallot, extra-virgin olive oil, lemon juice and garlic in a large bowl, season to taste with salt and pepper and mix well with your hands until the kale starts to soften (2-3 minutes). Toss through the beef, pumpkin, chopped broccoli, parsley and pepitas. Place salad on the middle of the plates and drizzle with the tahini dressing, to serve.
Make sure the char-grill is hot before you start cooking the beef, otherwise the meat will stick to the grill. The meat should sizzle as it makes contact with the char-grill.
Only turn the beef once during cooking to get the best crust and to prevent it from toughening. The more you fuss around with it, the tougher it will get.