Preheat the oven to 400℉. In a saucepan, bring some water to a boil with a pinch or two of salt.
Heat a cast iron or oven safe skillet (to 400℉). Add 1 tablespoon of olive oil. Add fennel, garlic, and shallot (if using). Stir and sauté until starting to brown lightly, about 6-8 minutes. Remove to a dish.
Add a drizzle of olive oil to the skillet. Next add the salmon pieces, top side down to the skillet. Sear over medium high heat for 3-4 minutes. Gently turn the pieces over. Add several lemon and orange slices to the top of the salmon pieces. Next add the fennel, garlic, and shallots back in, followed by the butter, white wine, lemon and orange juice, crushed red pepper, plus a pinch of salt. Simmer for a few minutes before moving to the oven.
Transfer the skillet to the preheated oven. Cook for 6-9 minutes or until the desired temperature of salmon is reached.
While the salmon is cooking, add your favorite gluten pasta to the boiling water. Cook until desired doneness. Drain, rinse and add a drizzle of olive oil.
Plate the pasta first. Remove any lemon or orange peels from the sauce. Spoon some sauce over the pasta. Add the salmon to each bowl. Divide the remaining sauce over the salmon and pasta. Top with crushed red pepper, if desired. Add fresh parsley or basil to finish.