In a small bowl, mix all of the tzatziki ingredients together. Chill in the fridge for at least an hour for the flavors to come together before assembling the layers. Make sure the grated cucumber is drained. Add grated cucumber into a paper towel, and squeeze excess liquid out.
Once tzatziki has chilled, you can layer the dip onto a large shallow platter. Spread the hummus evenly on the bottom, followed by the tzatziki, leaving a border of hummus showing. Sprinkle with tomatoes, roasted red peppers, scallions, and feta. Drizzle lightly with good olive oil and hot sauce if desired. Serve with crispy pita chips, warm naan bread, and fresh veggies for dipping!