- 1 small onion, finely chopped
- 1 teaspoon fine sea salt
- 1/2 pound tomatoes, chopped (1 cup)
- 4 teaspoons minced fresh jalapeño chile, including seeds
- 1 1/2 tablespoons fresh lemon juice
- 1 tablespoon fresh orange juice
- 1 teaspoon finely grated peeled fresh ginger
- 1/2 teaspoon mustard seeds
- 1/4 teaspoon turmeric
- 1 1/2 tablespoons olive oil
- 1/4 teaspoon black pepper
- Soak onion with 1/2 teaspoon sea salt in 1 cup cold water 15 minutes, then drain well in a sieve. Transfer to a bowl and stir in tomatoes, jalapeño, lemon juice, and orange juice.
- Cook ginger, mustard seeds, and turmeric in oil in a small skillet over moderately low heat, stirring, until seeds begin to pop, about 2 minutes. Stir into tomatoes with pepper and remaining 1/2 teaspoon sea salt, then let stand at least 1 hour for flavors to develop.
- Just before serving, drain chutney in a sieve set over a bowl, discarding liquid.