How to Make It
In a small skillet, stir the fennel and coriander seeds over moderate heat until fragrant, about 30 seconds. Add the crushed pepper and paprika and cook, stirring, for 30 seconds longer.
Transfer the spices to a blender. Add the oil and blend until almost smooth. Pour the spiced oil into a jar, cover and let stand overnight at room temperature. Strain the oil through cheesecloth and discard the spices.
Preheat the oven to 375°. Spread the pitas on 2 large baking sheets and toast for about 12 minutes, or until crisp.
Spread the Jerusalem artichokes on a rimmed baking sheet, cover tightly with foil and bake until tender, about 45 minutes to 1 1/4 hours, depending on their size. Remove them as they are done and let cool to room temperature. Using a small metal spoon, scoop out and reserve the flesh, discarding the skins.
In a food processor, puree the chickpeas and garlic. Add the Jerusalem artichokes, tahini and lemon juice and process until smooth. Season with salt and pepper to taste and let stand for at least 2 hours or refrigerate overnight.
Spoon the hummus into a bowl, drizzle with 2 tablespoons of the spiced oil and garnish with the parsley. Serve the crisp pita chips alongside.