Using a mortar and pestle, pound 1/2 small clove chopped garlic with 1/4 tsp. kosher salt. Pack a 1/2-cup measuring cup tightly with fresh basil leaves, then add half of it to mortar and pound to a coarse paste. Add remaining basil with 1 tbsp. chopped flat-leaf parsley and pound in. Stir in 1/4 cup extra-virgin olive oil and season to taste with pepper and more salt.