Greek Yogurt (Best Option)
1/4 cup Greek yogurt per 1/4 cup sour creamGreek yogurt has a similar consistency and tangy flavor to sour cream, making it an excellent substitute in tomato sauce. Its protein content helps maintain creaminess when heated, and its acidity complements the tomato's natural acidity.
To prevent curdling, add Greek yogurt off the heat or temper it by mixing with some warm sauce before combining fully. Use full-fat varieties to mimic the richness of sour cream.
The final sauce will be slightly thicker and tangier but maintains the creamy mouthfeel and balances the tomato acidity well.