Cut onion in half and slice half of the onion, set the other half aside
Blend half of onion, garlic, and pepper with a few drops of water to loosen
Blend tomatoes into a smooth puree and set aside
Heat saucepan over medium heat with oil
Add sliced onions and sautee until softened and tranlucent
Add onion blended onion mixure
When the onion puree reduces to half, add the tomato puree and cook until it reduces to half and the oil begins to settle at the top
Season the tomato stew with the seasoning cubes
Add spinach to the stew and cook down until spinach is softened (this will take longer to cook if spinach is frozen)
Add mushroom of choice and cook until tender and the oil begins to settle at the top
**optional** If the stew consistency is too tight then add some water to loosen it to your liking.
