Season oxtail with salt and pepper. If you have fatty oxtail, you can decide to trim some of the fat off. Leave them out in room temperate for 30 minutes.
Preheat a large pot, large dutch oven, on medium heat. Add avocado or olive oil.
When oil begins to shimmer, add oxtail. Brown one side for 2-3 minutes.
Turn your oxtail and add the thyme. Cook on the other side for 2 additional minutes.
Add onions and cook for another minute.
Add tomatoes, leeks, ginger, garlic, and Adobo. Cook for one minute.
Pour in the water and let it come to a boil. 8. Reduce to a simmer and cook until oxtail has softened (SEE NOTES). Add additional water (or beef stock) as needed.
Add carrots, bell peppers and potatoes. Cook until your desired texture is reached.
Transfer tender oxtail to a serving dish. Serve with rice and enjoy!