What would be the best way to install kitchen cabinets on a plastered over brick wall?
A French Cleat would work well in that situation - see this - http://www.newwoodworker.com/graphics/photos/artlstips/frenchcleat/frnchcletdiag400x264.jpg
I would put the cleat on the plaster wall with expansion lead anchors into the brick.
I agree, french cleat would be the best. You can use raw plugs or tapcons to attach to the wall.
A french cleat would work great but I don't have enough space on the back side of the cabinet for the cleat.
You can still use the Tapcon screws. http://www.itwbrands.com/ They are carried by most hardware and big box stores.