Caramelize the Onions: In a Dutch Oven or other heavy lidded pot, add the onions, olive oil, and sea salt. Saute on low heat, and stir with a wooden spoon for 25 minutes until the onions begin to reduce. After 25 minutes, add the vegan Worcestershire sauce and saute for 5 additional minutes.
While the caramelized onions are sauteeing: place the slices of bread on a sheet pan, and set aside.
In a small bowl, combine the minced garlic, garlic powder, olive oil, and red pepper flakes. Stir well, and set aside.
Place the sheet pan with the bread in the oven and broil on low for 2-3 minutes until the top turns lightly brown.
Remove bread from oven and flip the bread, so the toasted side is down. Brush each of the slices of bread with the garlic and olive oil mixture, saving about 1/2 of the mixture for later. Place the bread back into the oven and broil for 2-3 minutes until golden brown, but keep an eye so the bread doesn't burn.
When the garlic bread has finished toasting, top with the caramelized onions, and enjoy warm!