Mushrooms à la Grecque

3/4 cup golden raisins
4 cups small cauliflower florets
4 scallions, halved crosswise
1/3 cup plus 2 tablespoons extra-virgin olive oil
1 1/2 teaspoons coriander seeds, tied up in cheesecloth
1 medium onion, finely chopped
1 1/2 cups dry white wine
Bouquet garni (6 parsley stems, 2 leafy celery tops and 2 thyme sprigs tied with kitchen string)
2 teaspoons ground coriander
Salt
1 1/2 pounds small mushrooms
1 tablespoon fresh lemon juice
Freshly ground pepper
4 plum tomatoes, cut into 1/4-inch dice
2 tablespoons tomato paste
2 tablespoons small mint leaves
2 tablespoons chives cut in 1-inch lengths

In a saucepan of boiling water, blanch the raisins for 2 minutes. Using a slotted spoon, transfer the raisins to a plate; let cool. Blanch the cauliflower florets until crisp-tender, about 2 minutes; transfer to the plate. Blanch the scallions for 1 minute; add to the cauliflower. Thickly slice the scallions crosswise.
In a large skillet, heat 1/3 cup of the olive oil with the coriander seeds. Add the onion, cover and cook over moderate heat until softened, about 4 minutes. Add the wine, bouquet garni and ground coriander; season with salt. Cover and cook for 5 minutes. Add the mushrooms and lemon juice, season with salt and pepper and simmer over moderately high heat, stirring, until the mushrooms are just tender, about 5 minutes.
Transfer the mushrooms to a bowl. Add the tomatoes, tomato paste and raisins to the skillet and simmer until the sauce is thickened, about 8 minutes; discard the bouquet garni and coriander seeds. Add the mushrooms to the sauce and bring to a boil, then season with salt and pepper. Let cool.
Pat the cauliflower and scallions dry and put in a bowl. Add the remaining 2 tablespoons of olive oil, season with salt and pepper and toss. Mound the mushrooms on plates and top with the cauliflower and scallions. Garnish with the mint and chives and serve.