How to Make It
Score the cut sides of the eggplants in a crisscross pattern and sprinkle with 1 tablespoon of salt. Arrange the eggplant halves, cut side down, on a large platter, cover with a baking sheet and weight down with cans. Let stand for 1 hour to press the moisture from the eggplants.
Preheat the oven to 375°. Spread 1 tablespoon of the olive oil on a baking sheet. Pat the eggplants dry with paper towels and set them, cut side down, on the baking sheet. Bake the eggplants for about 1 hour, or until very soft. Let cool slightly, then remove the skin and seeds and finely chop the pulp. Put the pulp in a strainer and press out as much moisture as possible.
Transfer the eggplant to a food processor and stir in the garlic and mustard, some pepper and the remaining 1 tablespoon of olive oil. Refrigerate the eggplant caviar overnight. Let the eggplant caviar return to room temperature, then spread each Crostini Toast with a heaping teaspoon of the eggplant caviar and serve.