Quarter tomatoes lengthwise and arrange on a parchment paper-lined baking sheet. Drizzle with olive oil just to coat and season very lightly with salt and pepper. Place in convection oven with fan on or dehydrator at 250ºF for 3 hours. Remove from oven and cool to room temperature; then, dice very fine. Turn into mixing bowl with remaining ingredients and combine thoroughly, using a rubber spatula. Set aside to chill for 2 hours.