- Prepare the jars and lids in boiling water.
- In a small bowl, dissolve the cornstarch in 2 tbsp (30 ml) of the lime juice. Set aside.
- In a large pot, combine the remaining ingredients. Bring to a boil and simmer over medium heat for 25 minutes, stirring a few times. Add the cornstarch mixture and continue cooking for 2 minutes or until the mixture thickens slightly. Adjust the seasoning.
- Spoon the salsa into the hot jars, leaving 1 inch (2.5 cm) of space at the top. Remove air bubbles with a non-metallic utensil and wipe the rim of the jar with a clean cloth.
- Centre the lids (discs) on the jars and screw the rings down until the point of resistance, then tighten another eighth-turn, without forcing.
- Place the jars upright on the canning rack in the pot of hot water. Make sure the jars are covered by at least 1 inch (2.5 cm) of water. Cover. Bring to a boil over high heat. Process for 15 minutes from the moment the water starts to boil.
- Remove the jars from the water.
Canned tomatillos can be found in the Mexican products section in some grocery stores. You can also find fresh tomatillos in some public markets when they’re in season, from August to October. You will need 2 cups, coarsely chopped like the tomatoes.