Cauliflower rice burrito bowl

Name: Cauliflower rice burrito bowl
Ingredients: 1 can black beans, drained and rinsed; 1 cup frozen corn kernels; 2 tablespoons water; 1/2 teaspoon chilli powder; 1/2 teaspoon ground cumin; 3/4 teaspoon salt, divided; 1 tablespoon olive oil; 1/3 cup chopped fresh coriander, divided; 1/4 cup freshly squeezed lime juice (from 2 to 3 medium limes); 1 cup diced or shredded cooked chicken (optional), warmed if desired.; 1/2 cup store bought salsa; 1 medium avocado, peeled, pitted, and sliced; 1 head cauliflower, any size; 1 tablespoon olive oil or butter, optional; Salt, optional