Sticky Sesame Cauliflower

Name: Sticky Sesame Cauliflower
Ingredients: 1 cup all-purpose gluten-free flour; 1/2 teaspoon garlic powder; 1/4 teaspoon salt; 1 cup water (plus more as needed); 1 small head of cauliflower (cut into florets (scant 4 cups of florets)); 2 and 1/2 teaspoons toasted sesame oil (divided); 1/2 inch ginger (minced or grated); 2-3 cloves garlic ((to taste), minced or grated); 3 and 1/2 tablespoons agave nectar ((or less, to taste)); 2 and 1/2 tablespoons soy sauce; 1 teaspoon rice vinegar; 2 tablespoons tomato paste; 1 teaspoon chili paste like sriracha; battered cauliflower ((above)); sticky sesame sauce ((above)); toasted sesame seeds (for serving); chopped green onions (for serving)