A common failure in writing I notice is the over- and under-detailing of people, places, things, and events.
If your character is in a high-stress action-scene situation where every second counts, they'll be paying attention to the generally noticeable things such as the area they are in, how many people and of what groups (us vs. them, red vs. blue, etc.) are there, what items they have at their disposal, and what noteworthy things occur (a person firing a gun, glass shattering, the Earth trembling, etc.).
In a calm, relaxed scene, it only makes sense that they'd people-watch, note calming environmental changes, and pick up on details like facial features, diction, and apparel.
A great movie to watch in order to see this rule in action is Green Book, which gives you plenty of opportunity to note the high cheek bones, Penny Brown skin tone, the diamond head shape, the prim attire, and the preferential, eloquent diction of the main character, Doctor Donald Shirley. At the same time, with the situation where a police officer pulls the car over in the rain, we can remember what was generally said since our focus is pulled towards the words, but the details of what the racist police officer looks like are easily forgotten. (Whether the story is true or false in how it was told is a separate matter I'd rather not get into.)
When it comes to writing, you just need to describe the man based off what you can reasonably assume your character would notice. If you think your character would only notice his skin is black, then call him a black man. If you think your character would see the man in a symphony of purple prose, then describe the man in great detail. As for what he looks like specifically, though... that's on you. It's worth noting, that there is very little obvious difference in facial structure between a black person versus a white person. The things most affected by race are hair, eye, and (obviously) skin color. He can be tall or short, thin or fat. He can have any facial shape, a large or small chin or nose. His lips can be large like the caricatures of ole', or they can be thin like a thread. Describe him as you would any other character, but mention his skin color so that the audience knows. If you do, I recommend doing it in a way where you make it as little about his race as possible, though. For example:
And most hauntingly, a twelve-year-old girl from District 11. She has dark brown skin and eyes, but other than that, she's very like Prim in size and demeanor. Only when she mounts the stage and they ask for volunteers, all you can hear is the wind whistling through the decrepit buildings around her. There's no one willing to take her place.
This line comes from The Hunger Games and is describing Rue. So many people read this then were outraged when Rue was cast as Amandla Stenberg even though the story says she is a black girl. Why? Because Rue being black wasn't made a big deal of in the text. The fact she was a young girl was more important. The fact she reminded Katniss of Prim overshadowed all mention of skin tone. People forgot she was black and instead viewed her as white, Hispanic, or Asian because her race wasn't a central focus of her character. This is detailing done right. You describe the things your character would see. In Katniss's case, when she looked at Rue, she could only see a little girl who reminded her of her sister. What does your MC see when s/he looks at the man you're trying to describe?