Slice whole oranges into half-inch thick circles. Using a sharp paring knife, cut away all rind and pith. Arrange citrus circles on a serving dish. Layer with fennel and shallot. Arrange avocado slices on top. In a small bowl, whisk olive oil, white wine vinegar, honey, and salt to combine. Pour dressing over salad. Top with salt, fennel fronds, and mint leaves.