INGREDIENTS
2 tbsp
olive oil
1
small yellow onion, halved and sliced into ¼-inch thick slices
1 tsp
crushed red pepper flakes (or start with ½ tsp. for less spice)
2 28 ounce cans
whole tomatoes
1 1/2 cups
water
1/4 cup
loosely packed fresh basil leaves
Kosher salt and freshly ground black pepper