Heat the olive oil in a nonstick skillet. Add the red pepper and celery and cook over moderately high heat, stirring, until the vegetables are just softened, about 2 minutes. Add the scallions and ginger and cook until the scallions are wilted, 1 to 2 minutes. Stir in the cumin, turmeric and cardamom and cook until fragrant, about 1 minute. Add the cream and boil until reduced by half, about 6 minutes. Transfer to a bowl and let cool slightly.