yields 3/4 - 1 cup (about 200 mg)
1 large poblano pepper
1 cup full-fat canned coconut milk
scant 1/2 tsp fine sea or kosher salt
Heat the oven broiler with a rack in the top position.
Trim, seed, and halve the pepper lengthwise. Remove any thick membranes. Place peppers cut-side down under the heat sources, and broil until thoroughly blistered, 10-15 minutes. (Check the oven occasionally. If the broiler kicks off, open the door until it comes back on.)
Carefully add peppers to a small brown paper bag, or a small bowl covered tightly with a clean kitchen towel, and let rest 10 minutes. Peel off and discard blistered skins.
Transfer pepper, milk, and salt to a quart jar and blend thoroughly with an immersion blender. Transfer to a small pot, and bring to a boil over medium heat. Reduce heat slightly to keep a strong simmer, and cook, stirring, five minutes. Remove from heat, let cool, and store in the fridge in an airtight container, where the sauce will thicken, until ready to use.