In a medium bowl, combine the hummus, 1/2 cup feta, and green onions.
Place a small bowl or drinking glass in the center of a large round platter (about 12.5 inches in diameter). If you plan to place a bowl of pita chips or veggies at the center of the finished wreath, use that bowl (or a similarly sized glass) to ensure the hole in the middle of the wreath is the right size. Use a rubber scraper to spread the hummus mixture in a circle all around the bowl/glass. Remove the bowl/glass from the center using a gentle, upward twisting motion. If needed, carefully insert the tip of a toothpick under the edge of the bowl/glass to help it release.
In another small bowl, toss the parsley, oil, and salt until the parsley is thoroughly coated and the oil and salt are evenly distributed. Spoon the parsley mixture in a circle on top of the hummus layer, leaving a small border of hummus showing all around.
Place the halved cherry tomatoes, cut-side down, randomly throughout the parsley layer, so they look like Christmas ornaments.
If making the optional bow out of red pepper, cut one broad, flat side off the pepper, and gently but firmly press a metal, bow-shaped cookie cutter through the pepper slice to cut out the bow. Place the bow on the wreath.
Sprinkle the entire wreath lightly with a dusting of 1 to 1 1/2 tablespoons very finely crumbled feta, to look like snow. Adjust the exact amount of feta depending on the diameter of your wreath – you want it to look like just a light dusting, without using so much feta that it hides the other ingredients.
Serve immediately with dippers of your choice, or cover and refrigerate for up to 1-2 days. (See make-ahead tips below.)