Sauce: Peel and chop the shallots. Cook them in 30 ml (2 tablespoons) of olive oil for 3 to 4 minutes until they are tender. Add the blueberries, 80 ml (1/3 cup) of water, the mustard, and the jam. Cook, stirring constantly. Let simmer for 3 to 5 minutes. Mix the cornstarch with a little water until the mixture is smooth. Add to the blueberry mixture, stirring well. Bring to a boil and cook for 2 to 3 minutes. Add the salt. Let cool slightly.
Salad: Wash the endives, lettuce, and bell peppers. Cut the endive into cubes, slice the yellow bell peppers into thin strips, and chop the lettuce into small pieces. In a large bowl, mix the vinegar, salt, pepper, sugar, and olive oil. Add the salad and stir well.
Cheese: Sprinkle the top of the goat cheese with powdered sugar. Place the goat cheese on a baking sheet lined with aluminum foil. Let it brown slowly on the preheated grill for 1 to 2 minutes. Remove the cheese from the oven and sprinkle with coriander.