Cauliflower and Red Onion Tacos

Name: Cauliflower and Red Onion Tacos
Ingredients: 1 large or 2 small or medium cauliflowers, broken into florets (about 6 cups); 1 red onion, cut in half lengthwise, then sliced crosswise across the grain; 1 to 2 garlic cloves (to taste), minced; 1/4 cup chopped cilantro; 2 tablespoons capers, drained and rinsed; 1/4 cup white wine vinegar or Champagne vinegar (to taste); 3 tablespoons extra virgin olive oil; Salt and freshly ground pepper; 1 or 2 chipotle chilies in adobo or pickled jalapeños, drained and thinly sliced (optional); 12 corn tortillas; 1 romaine heart, cut crosswise in thin strips (chiffonade); 3 ounces cotija or ranchero cheese