Place quinoa, stock and water in a medium saucepan over high heat. Bring to a boil, then cover and reduce to very low. Simmer gently for 10 minutes, remove from heat and set aside, still covered, for a further 10 minutes. Fluff with a fork and tip onto a serving platter.
Drizzle salmon with 2 tsp of the olive oil and a pinch of salt and pepper. Cook in a skillet over medium-high heat for 3 minutes per side, or until cooked to your liking. Remove salmon from pan and set aside to rest.
Add remaining 1 tsp olive oil and the sliced snow peas to the same skillet used for the salmon. Sautee over medium-high heat for 1 - 2 minutes until bright green and tender-crisp. Add snow peas to the platter with the quinoa and toss to combine.
Place 1 tsp miso, 1 tsp brown sugar and 2 tbsp water in a heavy-based skillet over medium-high heat. Whisk to combine and bring to the boil. Add custard apple pieces and stir for 20 - 30 seconds only. Remove pan from heat and spoon the caramelised custard apple onto the quinoa. Reserve any pan juices.
Whisk together the reserved pan juices, remaining miso, rice wine vinegar, soy sauce, sesame oil and sesame seeds to make a dressing.
Toss quinoa with the spinach and coriander. Flake salmon over the salad, and drizzle with miso dressing to serve.
