For the salsa, place tomatillos in food processor or blender and pulse into puree. Add salt, cilantro, mint, peppers, garlic, onion, avocado, and juice of 1 lime, and combine until fairly smooth. Adjust seasoning and thin with water if too thick. Store in fridge up to 2 weeks.
For the poblanos, char them over an open flame on burners or under a hot broiler until blistered all over. Cool poblanos in covered bowl. Peel and seed the peppers, then cut into thin strips or “rajas.”
For the onions, heat a medium skillet over medium heat and add 2 tablespoons olive or canola oil. Cook the onions slowly until sweet and very soft, but not caramelized, 20-25 minutes. Add water if they begin to brown and lower heat.
For the pork, season with salt and pepper and baking soda and chill uncovered 1 hour or overnight. (This will help the pork get extra-crispy once crumbled.)
Heat a large cast iron or nonstick skillet with 2 tablespoons oil over medium-high. When pan smokes, add pork and brown well, crumble, and season with cumin and oregano. To a food processor, add serrano peppers, scallions, garlic, chard, and parsley and cilantro. Pulse until smooth. Stir mixture into pork, adjust salt and pepper and add juice of 1 lime.
To serve, place cheese on hot tortilla, top with pork, poblanos, onions and a little raw salsa.