For the Beets: Preheat oven to 375 degrees F. Line a 8×8baking pan with aluminum foil. Place the beats in the prepared pan. Drizzle with oil. Cover pan with additional foil to seal. Roast the beets until tender, about 50 minutes. Let the beets stand covered at room temperature 20 minutes. Once cool enough to handle, peel the beets. Place in bowl, cover and chill at least 1 hour.
For the Oregano Vinaigrette: In a small mason jar add the olive oil, red wine vinegar, garlic, lemon juice, lemon zest, oregano and salt and black pepper to taste. Cover and shake vigorously for about 20 seconds.
To Assemble: Thinly slice beets. Arrange the beets in concentric circles on a large serving platter. Drizzle with the oregano vinaigrette and cotija. Garnish with additional oregano leaves.