Pasta with Crab and Avocado Sauce

Yield:	4 Servings
Categories:	Pasta, Fish

		Stephen Ceideburg
1	sm	Onion
1		Piece of fresh ginger, 1 cm grated
1/2	tb	Olive oil
150	ml	Fish stock
60	ml	Dry Sherry
		Salt to taste
		Cayenne to taste
1	lg	Avocado
1/2		Lemon, juice only
300	g	Crabmeat
		Cooked pasta for four