Preheat oven to 220°C/ Fan 200°C/ Gas 7. To make the coconut dressing, place the coconut milk, lime juice and grated ginger in a bowl and whisk to combine. Set aside.
Place the quinoa, water and ginger slices in a medium saucepan over high heat and bring to the boil. Cover with a tight-fitting lid and reduce the heat to low. Cook for 10 minutes. Remove from the heat, discard the ginger and allow the quinoa to stand, covered, for 5 minutes. Remove the lid and set aside to cool completely.
Heat a griddle pan over high heat. Place the chilli flakes, oil and garlic in a small bowl and mix to combine. Brush the steak and tender-stem broccoli with the chilli mixture and sprinkle with salt and pepper. Cook the steak to your liking, set aside and allow to rest for 10 minutes.
Cook the tender stem broccoli in the char-grill pan for 2–4 minutes each side or until lightly charred and tender. Place the quinoa, tender-stem broccoli and cashews in a bowl and toss to combine. Thinly slice the beef and serve with the quinoa salad and coconut dressing.