- ½ cup (112g), plus 4 Tbsp (57g) unsalted butter, divided
- 1 small yellow onion, sliced
- 1 (28 oz) can whole peeled San Marzano tomatoes, hand crushed
- 1 cup (240g) water
- Kosher salt, to taste
The easiest and most delicious tomato soup recipe ever is ready in just 10 minutes.