Cauliflower "Rice" Tabbouleh

1/2 medium head of cauliflower (about 1 pound), coarsely chopped
5 tablespoons extra-virgin olive oil, divided
1 teaspoon (or more) kosher salt, divided
2 cups (packed) flat-leaf parsley leaves with tender stems
1 cup (packed) mint leaves
2 scallions, white and pale-green parts only, sliced
1 garlic clove, coarsely chopped
1 teaspoon finely grated lemon zest
3 tablespoons fresh lemon juice
1/4 teaspoon crushed red pepper flakes
1/2 medium cucumber (about 8 1/2" long), cut into 1/4" pieces
6 ounces cherry tomatoes, quartered

Grate cauliflower with the coarse grater disk on a food processor or the largest holes on a box grater until rice-like in texture.
Transfer to a large, microwave-safe bowl and toss with 1 Tbsp. oil and 1/4 tsp. salt.
Cover with plastic wrap and microwave on high 3 minutes.
Carefully remove plastic wrap, spread cauliflower "rice" on a rimmed baking sheet, and let cool.
Wipe out food processor, if necessary, and fit with chopping blade.
Pulse parsley, mint, scallions, garlic, lemon zest, lemon juice, 3/4 tsp. salt, and remaining 1/4 cup oil until herbs are coarsely chopped.
Transfer to a large bowl and stir in red pepper flakes.
Add cauliflower, cucumber, and tomatoes and gently toss to coat.
Season with additional salt, if necessary.