Chess/Puzzles/Directmates/Two-move 4/Solution

It is quite simple to show that the only move black could have made to reach this position was b7-b5. Thus, a5 can take b5 en passant.

1.a5xb6 a3

2.b7#

a b c d e f g h
8 8
7 7
6 6
5 5
4 4
3 3
2 2
1 1
a b c d e f g h