Preheat the oven to 450°. Place a small skillet over medium heat and add the curry powder. Toast for 1½ minutes, stirring frequently. Remove the curry powder from the heat and set aside.
Place a large braising pan over high heat and add the olive oil, moving the pan around so the oil coats the bottom of the pan. Add the onion and stir for 3 minutes, then lower the flame to medium and add the garlic and ginger, stirring until the garlic begins to brown, another 3 minutes. Add the lamb shoulder and the banana slices and stir to combine. Add the cumin, coriander and toasted curry powder and stir until the pan's contents are aromatic, about 4 minutes.
Increase the temperature under the braising pan to high heat; add the red wine and cook for 5 minutes. Stir in the chicken stock, cover and remove from the stovetop. Place the pan in the oven and bake for 2 hours and 15 minutes, until the lamb is tender. Season with salt and pepper and serve hot over the jasmine rice.