Cook the quinoa. Rinse 1 cup of quinoa under cold water to remove bitterness. Add to a saucepan with 2 cups of water and a pinch of salt.
Bring to a boil, then cover and simmer for 15 minutes, or until the water is absorbed. Turn off the heat and let it sit, covered, for 5 minutes. Fluff with a fork and spread on a tray to cool.
Make the balsamic glaze. Add 1/2 cup balsamic vinegar to a small saucepan.
Bring to a gentle simmer and cook until reduced by about half, 8–12 minutes. For a smoother, less sharp finish, whisk in 1–2 teaspoons honey near the end. The glaze should coat the back of a spoon.
Remove from heat to thicken slightly as it cools.
Prep the tomatoes and mozzarella. Halve the cherry tomatoes. Drain the mozzarella and pat dry. If using larger mozzarella, cut into bite-size pieces.
Slice the basil. Stack the leaves, roll them up, and slice into thin ribbons (chiffonade).
Save a few whole leaves for garnish.
Mix a quick dressing. In a large bowl, whisk 3 tablespoons olive oil, the minced garlic, a pinch of red pepper flakes, a squeeze of lemon (optional), and a good pinch each of salt and black pepper.
Toss the salad. Add the cooled quinoa, tomatoes, and mozzarella to the bowl. Toss gently to coat in the dressing. Taste and adjust seasoning.
Fold in most of the basil, reserving some for the top.
Finish with balsamic glaze. Transfer to a serving platter or bowl. Drizzle generously with balsamic glaze and the last spoonful of olive oil. Scatter the remaining basil over the top.
Serve. Enjoy immediately at room temperature, or chill briefly for a slightly cooler salad.
Add a final pinch of salt right before serving to make the flavors pop.