"Gravitational lensing is so strong, we can see the back of the star"
This is true for black holes as well, when we look straight at a black hole, the em radiation coming to our eyes may not be coming in a straight path, they may get curved so much that the "stuff" behind the black hole would appear to us, and our night sky would contain two copies of the body, a result of light curving in different paths around the black hole