Preheat oven to 350 F.
Rinse leeks thoroughly to remove dirt. Halve lengthwise, slice, and pat try with paper towel.
Combine leeks, onion, chili powder, orange juice, chicken broth, and 1/2 tsp salt. Bring to a boil on high heat. Turn heat to medium and simmer until leeks are tender, around 30 minutes.
Add salmon to baking dish. Brush lightly with EVOO and sprinkle with salt and pepper. Bake 20 minutes.
Meanwhile, add potatoes and saffron to a pot and cover with water. Boil over high heat about 20 minutes or until fork-tender.
Drain potatoes. Return to pan with milk and remaining 2 tbsp butter. Season with salt and pepper and mash.
When leeks are done, remove from heat and stir in 2 tbsp butter.
To serve, add potatoes to plate and top with salmon, leek mixture, and chives. Bon Appetit!