I blend in small amounts but I use a Magimix with standard blade. Do not use a jug (smoothie type blender) as they don't seem to get on with onions too well. I usually half fill the Magimix bowl, any more and it goes into vortex and doesn't blend too well. If you really want the best approach (a professional cheffy thing), use a mouli sieve, which is a conical sieve with a hand operated blade to grind and extrude the pulp. You can get these for as low as 45 squid from Nisbets.
CP