Heat about 1/2-1 tbsp. olive oil on medium in 2 separate skillets. (small & medium)
Slice 1/2 yellow onion into thin strips and place in smaller, heated skillet.
Place 6 plant-based bacon strips into other heated skillet.
Stir onions occassionally and flip bacon at least once to fully cook all thoroughly, set both skillets aside once finished.
Now thinly slice tomato and avocado, set aside.
Half bagel if not already halved and place in toaster for desired time.
Spread hummus on bottom half of bagel while spreading vegan mayonnaise on the top half.
Assemble bagel by placing bacon strips, sautéed onions, tomato, avocado, and spinach leaves on top of the hummus-spread bagel half.
Top with top half bagel and enjoy.