For the endive: In a medium skillet over medium heat, heat the olive oil. Add the sugar and endive quarters and brown for about 2 minutes. Next, add the piquillo peppers, garlic and red onions and cook about 3 more minutes. Deglaze with the vegetable broth and add the beans. Cook until the broth is slightly reduced, about 4 minutes. Smash some of the beans to further thicken the sauce. Keep warm.
For the gremolata: Combine together the mint, parsley, lemon zest, garlic, red pepper flakes and some kosher salt in a small bowl. Add enough extra-virgin olive oil to bind the mixture together, 1 to 2 tablespoons.
For the fish: Sprinkle the halibut fillets on both sides with salt and pepper. In a large saute pan, add the canola oil and heat on high until there are small wisps of smoke coming from the sides of the pan. Add the fish to the pan and cook until golden, about 4 minutes. Flip and cook until firm but still translucent in the center, 4 more minutes.
Spoon some endive onto each plate and then a piece of halibut. Top with some of the gremolata.