Put it in a paper bag and wait.
The one on the top I bought a few days ago. Still green. The one on the bottom has been in this brown paper bag for about a month. It started out as green as the one on top. It’s dried and wrinkled but it doesn’t affect the flavor. It just gets better.
These are Anaheim peppers:
An Anaheim pepper is a mild variety of the cultivar ‘New Mexico No. 9’. The name ‘Anaheim’ derives from Emilio Ortega, a farmer who brought the seeds from New Mexico to the Anaheim, California, area in 1894.
They are just a little hot, not as hot as a jalapeno, and very tasty:
The New Mexico green chile pepper flavor has been described as lightly pungent similar to an onion, or like garlic with a subtly sweet, spicy, crisp, and smoky taste. The ripened red retains the flavor, but adds an earthiness and bite while aging mellows the front-heat and delivers more of a back-heat. The spiciness depends on the variety of New Mexico chile peppers.