Pour the olive oil into a large skillet over medium heat. Add the mustard seeds and cook, shaking the pan frequently, until they start to pop, 1 to 2 minutes.
Stir in the tomatoes, chile, and ginger. Cook, stirring occasionally, until the tomatoes collapse and exude their juices and the juices thicken, 5 to 7 minutes. Stir in ½ cup water and the sugar. Cook, stirring occasionally, until the tomatoes are very soft, 8 to 10 minutes. Let the mixture cool slightly.
Scrape the tomato mixture into a blender, along with the peanuts and salt. Blend briefly until incorporated but still slightly chunky. Blend in up to ½ cup more water, as needed, to achieve a pourable but thick consistency.
Serve immediately, refrigerate in an airtight container for up to 1 week, or freeze for up to 3 months.