Tart Dijon mustard and fresh thyme in a creamy sauce can elevate any variety of fish. Serve the fish with warm roasted parsnips and a sweet-tart kale salad on the side.
Toss parsnips with cooking oil (portion for the parsnips) and season with some salt. Spread them out on the prepared sheet pan and roast, shaking the pan halfway through cooking, until parsnips are tender, 20 to 25 minutes.
While parsnips are cooking, in a large serving or mixing bowl, whisk together vinegar and honey. Add olive oil while whisking. Pile kale on top but wait to toss until right before serving.
Heat a large nonstick pan over medium-high heat. Add cooking oil (portion for the fish) and then fish to heated oil. Sear fish on both sides until golden brown (don’t worry if the fish isn’t cooked all the way through, it will finish in the sauce). Set fish aside and return pan to heat.
To heated pan add butter and shallots. Saute until shallots are soft, ~2 minutes. Stir in flour until no dry spots remain. Add stock and mustard while whisking. Add thyme sprigs. Bring to a simmer and continue cooking until sauce is thick, 1 to 2 minutes.
Pour heavy cream into pan and then add fish back to pan. Cover pan with a lid or foil. Simmer fish in sauce until cooked through, ~2 minutes more. Taste and season with some salt, if needed.
Add cheese and parsnips to kale salad. Enjoy fish with salad on the side.