This is moist and full of flavour, without any fat, other than what was naturally in the fish. Add more black peppercorns to the spice mix if you want more kick. You can make the spice mix up to a week ahead and the fish may be cooked a day in advance.
Place the coriander seeds, black peppercorns, mustard seeds, juniper berries, and fennel seeds into a coffee grinder or food processor and grind them into small pieces (making sure none are left whole) but not to a powder. If you use a food processor and some of the spices are still too big after processing, crush them using a mortar and pestle, or put them in a resealable plastic bag and smash with a rolling pin.
Transfer the ground seed and spice mix to a small bowl. Add the brown sugar, garlic powder, onion powder, paprika, cloves, and salt, and mix well.
Spread the spice mix on a plate and press each slice of salmon into the mix to cover it completely. Use all the spice mix. Place the fish on a roasting tin, leaving space between the pieces. Let the fish sit at room temperature for 30 minutes, covered with cling film, or refrigerate it if you will be cooking it later.
Preheat oven to 200°C. Bake the salmon for 20 to 22 minutes, 20 minutes if you like it a little pink inside, longer if you want it fully cooked. Serve the fish hot or at room temperature.
Recipe adapted from The Healthy Jewish Kitchen, Sterling Epicure