In large skillet, heat oil. Add shallot, garlic, and fennel seeds; heat for 2 minutes, stirring occasionally. Pour in port and simmer for 5 minutes. Add 1 1/2 cups water, cranberries, honey, thyme, lemon zest, red pepper flakes, and salt to skillet. Return to boil, reduce heat to medium low, and simmer for 10 minutes.

Carefully place halibut in skillet with sauce, leaving about 1 inch between pieces of fish. Return to boil, reduce heat to low, and simmer gently with skillet partially covered for 3 minutes. Carefully flip halibut and continue cooking at slight simmer until fish is heated to internal temperature of 145 F, or has turned opaque throughout flesh.

Remove fish from skillet and place in shallow serving bowls. Boil cranberry sauce over medium-high heat, uncovered, until liquid is reduced by about half.

Add cranberry sauce to bowls with halibut and garnish with hazelnuts and parsley.