Take 3-4 large rectangular tin trays and add the halved tomatoes, cut/flesh side up. Liberally sprinkle all-over them the coarse salt.

Place the tin trays in the sun while covering them with a thin transparent cloth and let the sun do its magic. Avoid keeping them outside during the evenings in case of humidity. After 3-4 days the tomatoes should be ready, they should have a leathery soft texture.

As you will not be using all them immediately, you can either store them in sterilized glass containers toped-up with oil and refrigerate for some months.