Accessing page media or pagemediaselect from twig template?

I have a custom modular template/blueprint for reviews that is loosely based on the features template from Anitmatter. I'm trying to add a pagemediaselect option to the feature loop. In the blueprint, I have

.avatar:
   type: pagemediaselect
   label: Avatar

Which produces the drop-down to select the image option in the admin. But in the twig template, I'm not able to get the image to show up. I think I've read everything in the documentation and in the forum, this post is the closest that I've gotten. https://getgrav.org/forum#!/theme-development:access-to-pagemediaimages

Using

<img src="{{ page.url }},{{ review.avatar }}">

(replaced "features" with "reviews" in the blueprint)
I'm able to get output this:

img src="http://yisraels-macbook-pro.local:5757/crawfordmendez/modular/_04reviewsdemo-avatar-bowie.jpg">

For reference, an image url that works correctly through the callout module looks like this:

http://yisraels-macbook-pro.local :5757/crawfordmendez/images/1/8/1/2/a/1812abfd6068f0147269a3b8472b271b6c3a53da-demo-profile-image.jpeg

Thanks in advance!!

So as I was reading back through my post, I had an idea and got it working. I just needed a forward slash between {{page.url}} and {{review.avatar}}.

But, is that the proper way to do it?

I use this form aswell although I would really like to know if it's the best way, too.

Your solution works but you need indeed to add a slash at the end of theme_url. An easier way is to rename your image selection in the blueprint and name it header.review
Then, you can access your image with {{ page.media[header.review] }}
Remember that page.media will generate the img html tag like this <img src="http://yourdomain/yourimage.jpg">