Cook the kaniwa: Rinse thoroughly. In a medium saucepan, bring 2 cups of salted water to a boil. Add kaniwa, lower the heat, and simmer for 15–20 minutes until tender. Let it cool completely—about 1 hour.
Mix the veggies: In a bowl, combine tomatoes, cucumber, parsley, mint, and red onion. Add the cooled kaniwa and toss gently.
Make the dressing: In a small bowl, whisk olive oil, lemon zest, lemon juice, and salt. Pour it over the salad and mix to coat.
Chill and serve: Serve at room temperature or chilled. Perfect for sharing—or not.