Steps
1. Start by preparing the tomatoes. If using fresh tomatoes, blanch them in boiling water for a minute, then peel and chop them.
2. In a large skillet, melt the butter over medium heat.
3. Add the chopped onions to the skillet and sauté until translucent, about 5-7 minutes.
4. Add the chopped tomatoes to the skillet, stirring to combine with the onions.
5. Season with salt, pepper, and oregano, and let the mixture simmer for about 20-25 minutes, stirring occasionally.
6. If desired, add lemon juice to balance the flavors. Taste and adjust seasoning if necessary.
7. Once the sauce has thickened, remove from heat and let it cool slightly before using or storing.