The "Larsen" or "van Geet" Opening, the idea of which is to take control of the dark squares in the centre from afar.
1... e5
To be honest I don't know what "theory" thinks is the best response to White's set up. I just thought of occupying and strong pointing some of the squares White is trying to control.
2. Bc1b2 Nb8c6 3. e3 d5
Aiming at full occupation of the centre and free running bishops.
4. Bf1b5
Threat: 5. Bxc6+ bxc6 6. Bxe5 winning a pawn.
4... Bf8d6
Defends the e pawn and occupies an important diagonal.
5. Bb5xc6
I don't like this exchange which seems to weaken the light squares in White's half of the board and leave black with two bishops in a position that is fluid. Sure White develops his g1 knight to f3 with tempo but this is easily defended with simple developing moves.
5... bxc6 6. Ng1f3 Qd8e7 7. O-O Bc8g4
Further restraining the f3 Knight which is difficult to unpin. e4 winning the knight is threatened. Oh, for a light squared bishop to sit on e2!
8. h3
A further weakening move that whilst more or less forced does nothing to help White's predicament.
8... h5
Bringing about the attacking set up that is now commonly called the "fishing pole". Black offers the bishop to open the h file against the white king. after 9. hxg4 hxg4 White's only king-side defender is prodded away by the pawn on g4 and the black Queen can access h4 threatening an unstoppable mate on h1.