Season the fillets with salt and pepper. Heat 2 Tbs. of the olive oil in a large skillet over medium-high heat. When it shimmers, add the fillets, skin side up, and sear until just golden brown, about 4 minutes. Flip and sear the skin side for 4 minutes. Transfer the fillets to a plate; if the skin sticks to the pan, discard it.
Add the remaining 1 Tbs. oil and the sliced fennel to the pan, season with salt and pepper, and cook, stirring occasionally, until softened somewhat and browned in spots, about 4 minutes. Stir in the garlic and cook for 1 minute. Pour in the wine, immediately cover the pan tightly with a lid or foil, reduce the heat to medium, and simmer briskly until the fennel is tender, about 8 minutes. (Check halfway through; if the fennel is dry, add 2 to 3 Tbs. water). Stir in the tomatoes and their juices, 1/2 cup water, and 2 Tbs. of the herbs. Cover and simmer for another 5 minutes. Taste the broth for salt and pepper
Return the halibut to the pan, settling the pieces skin side down into the broth, and pouring over any accumulated juices. Cover tightly and simmer until the halibut is cooked through, about 4 minutes. Carefully lift out the halibut; taste the sauce, and season if necessary. Serve the fish in a shallow bowl with the sauce spooned over and around it. Garnish with the remaining 1 Tbs. herbs.
Serve over linguine or orzo tossed with herbs and olive oil.