Serves 6 INGREDIENTS For Sauce 1 jalapeño, deseeded and chopped fine (set aside half for tacos) ½ cup crème fraiche ½ cup fresh cilantro leaves, chopped fine Pinch of lime zest Juice of 2 limes Pinch of cumin 2 teaspoons salt For Tacos 2 tablespoons canola oil 1 medium red onion, cut in half and…