Step 1Chop the chocolate into small (one-fourth inch) pieces. Place in a metal bowl.
Step 2In a heavy-bottomed saucepan, heat the cream until it just begins to boil.
Step 3Pour the cream over the chocolate all at once. Let the cream sit for a few minutes to melt the chocolate. Using a rubber spatula, slowly stir in a circular motion starting in the center of the bowl and working your way out to the sides. Be careful not to add too much air to the ganache. Stir until all the chocolate is melted and thoroughly blended with the cream. Cool at room temperature for at least 4 hours. The mixture will firm as it sits.
Step 4Use a melon baller to scoop balls of the mousse into small wide tumblers, or minimalist small glass bowls. Pour 2 to 3 teaspoons of the oil around but not on each serving of mousse and sprinkle judiciously with the salt.