In a big pot, heat 2 cups (480 ml) of the vegetable oil over medium-high heat.
In a blender, combine the garlic, ginger, onions, and the remaining 2 cups (480 ml) vegetable oil.
Once the oil is hot, add the blended garlic/ginger/onion mixture. Cover the pot, as the shitɔ can bubble, and cook over medium-low heat, stirring periodically, for 20 minutes.
Add the tomato paste and continue cooking for another 20 minutes, stirring periodically.
Add the mushroom powder, powder pepper, umami spice blend, and bouillon cubes. Cook for another 25 minutes, stirring periodically. Taste for seasoning/salt and chiles and adjust for personal preference.
Store the shitɔ in an airtight glass jar or container, making sure the oil settles at the top and fully covers the shitɔ. The oil is used as a preservative. Only use a clean spoon to portion out the shitɔ to avoid introducing any bacteria into the jar. Shitɔ can last at room temperature or in the fridge for several weeks. I also like to split the shitɔ in two, freeze one half, and keep one half at room temperature. Once the first batch has been eaten, thaw the frozen batch and reheat it on the stovetop for 10 to 20 minutes to cook off any water the shitɔ accumulated during freezing.