Heat 2 tablespoons olive oil in a medium skillet over medium heat. Add the endive quarters, sprinkle with sugar and cook, tossing a couple of times, until lightly browned, about 2 minutes. Add the red onion, peppers and garlic and cook until the endive is wilted, about 2 more minutes. Raise the heat to high, add the beans, broth and rosemary and continue cooking, mashing some of the beans with a spoon to thicken the sauce slightly, 2 to 3 minutes.
Meanwhile, heat the remaining 2 tablespoons oil in a large skillet over medium-high heat. Season the halibut fillets with salt and pepper; place skin-side up in the pan and cook until golden, about 4 minutes. Turn and cook until firm but still translucent in the center, 4 more minutes.
Place the halibut fillets in 4 shallow bowls and spoon the beans and endive on top. Garnish with parsley. Photograph by Antonis Achiellos