Add half the coconut oil, red onion, water, and sugar to a medium pan. Cook on a high heat until reduced, about 5-10 minutes.
In a different pan, add remaining coconut oil, peppers, beet, and green onion. Fry until the vegetables are soft and brown, about 5-10 minutes.
In a medium bowl, marinate the lettuce and spinach in vegan butter, then add the ground peppercorns.
Slice and toast the bagel then layer the ingredients in the following order: hummus, lettuce, spinach, tomato, pepper/beet mixture, and top with the caramelised red onion.