Finely grate 2 tsp. zest from one of the lemons. Squeeze 1-1/2 lemons to yield 2 Tbs. of juice. Thinly slice the remaining half and cut each slice into quarters; set aside.
In a 10- to 11-inch straight-sided sauté pan, melt 3 Tbs. of the butter over medium heat until foamy. Add the endives, pears, lemon juice, lemon zest, and 1/2 tsp. salt; stir to combine. Cover, reduce the heat to medium low, and cook, stirring occasionally until tender, 15 to 20 minutes. Remove the lid and cook until the endives and pears are lightly browned in places, about 2 minutes. Remove from the heat and stir in the chives.
While the endives and pears cook, combine the flour and cornmeal in a shallow dish. Season the fish lightly with salt and pepper and then dredge it in the cornmeal mixture. Heat 1/2 Tbs. of the butter with 1 Tbs. of the oil in a 12-inch skillet over medium-high heat. Cook 2 of the fillets, flipping once, until golden-brown and cooked through, 2 to 3 minutes per side. Transfer to a clean plate. Wipe out the skillet and repeat with another 1/2 Tbs. butter and the remaining 1 Tbs. oil and fillets. Transfer to the plate with the other fish. Wipe out the skillet again.
Heat the remaining 2 Tbs. butter in the pan until melted and browned and then stir in the lemon slices and a pinch of salt. Add the wine, bring to a simmer, and reduce by half, 1 to 2 minutes. Season to taste with salt and pepper.
Divide the pear mixture among 4 dinner plates and top with a fillet. Spoon the lemon pan sauce over the fish, garnish with chives, and serve.