Chicken that's finger licking good!

I'm always surprised by how cheap chicken breast is in Japan - it's the cheapest meat to eat here! I made this for dinner tonight:

Mustard Chicken
2 x chicken breasts (chopped)
as much garlic as you like (chopped)
4 brown button mushrooms (sliced finely)
dash of mirin*
3 handfuls of spinach
1 tablespoon wholeseed mustard
1 tablespoon sour cream

Put chicken, garlic and mushrooms in a non-stick frypan and splash with mirin. Leave to sit covered for about 10 minutes.
Saute until chicken is cooked and then add spinach and mustard stirring well.
When ready to serve; quickly stir sour cream through.

Serve with pesto pasta.

*Mirin is a slightly sweet mild sake (Japanese rice wine) used for cooking - substitute white wine if mirin is unavailable.