How to Make It
Preheat the oven to 350°. Bring a medium saucepan of salted water to a boil. Add the cauliflower and cook for 2 minutes. Drain well, then spread the cauliflower on a paper towel–lined baking sheet to cool; pat the cauliflower dry.
In a small bowl, combine 1/2 teaspoon of salt with the baking powder, cumin, coriander, pepper and allspice. In a large bowl, using an electric mixer, beat the egg whites with a pinch of salt at high speed until firm peaks form. Fold in the cauliflower and the spice mixture.
Heat a large nonstick skillet. Very lightly oil the skillet. Drop tablespoons of the fritter batter into the skillet and cook over moderately high heat until browned on the bottom, about 2 minutes. Reduce the heat to moderate and cook until browned on the other side, about 2 minutes. Transfer the fritters to a large rimmed baking sheet. Repeat with the remaining batter, coating the skillet with oil as needed.
In a small bowl, blend the yogurt with the 1 1/2 teaspoons of olive oil and season with salt. Reheat the fritters in the oven, about 2 minutes. Garnish each fritter with 1/2 teaspoon of yogurt sauce and some caviar. Transfer to a platter and serve.