Roast the whole poblano chile over an open flame, turning occasionally, until charred all over. Let cool slightly and then skin, seed and puree it in a blender.
Rim a margarita glass with the lime wedge and dip in the Montreal steak spice.
Add the gin, maple syrup mixture, lemon juice, mescal and 1 1/2 ounces poblano puree to a cocktail shaker. Fill it with ice and shake. Fill the margarita glass with ice. Strain the drink over ice and garnish with a poblano chile slice.
Recipe courtesy of Eddie Garcia, Jade Bar, Phoenix, AZ