1. Preheat grill/oven to 425°F (220°C) and position rack to the highest position.
2. Line a baking tray with baking paper or foil.
3. Bring a medium saucepan of water to a boil.
4. Add a pinch of salt and udon noodles; cook according to package directions, then drain and rinse with cold water.

For the dressing

1. Combine lemon and orange juices and palm sugar in a saucepan.
2. Bring to a gentle boil and cook for 1 minute.
3. Add tamari and vinegar; return to a gentle simmer and cook for 1 minute, until slightly thickened.
4. Remove from heat and stir in zests; set aside to cool.
5. In a small dish, combine miso paste, tamari, honey, and mirin; mix well.
6. Marinate salmon fillets in the mixture, ensuring they are well coated.
7. Place salmon fillets on the prepared baking tray, skin side down, and bake for approximately 10 minutes, until a dark caramel color, basting once or twice.
8. Toss kale with olive oil and sea salt; add to the baking tray with the fish for the last 1-2 minutes of grilling, until crisped.
9. Remove fish from oven and set aside.
10. Toss cooked noodles with about 1/3 of the dressing, adding more to taste.
11. Divide noodles between two bowls.
12. Top with salmon fillet, crispy kale, avocado slices, spring onion, and sesame seeds.
13. Serve warm.