Remove all knobs, hinges and other hardware from the cabinets, using a screwdriver. Spread newspapers all around the area to protect the floor. Lay the disassembled cabinet doors on newspapers.
Apply chemical stripper over all the wood with a brush, covering it completely. Let the stripper sit on the wood for about 10 minutes, until the existing finish or paint starts bubbling and softening.
Scrape off the existing finish by pushing your plastic putty knife forward through the softened material. Take it all off.
Soak a nylon scrubbing pad in paint thinner and scrub the cabinet to remove all the residual finish. Let the wood dry overnight.
Buff the surface with medium sandpaper, by hand, sanding it in the direction of the wood grain. Wipe up the dust with a rag.
Brush wood stain thickly onto the cabinets, using a paintbrush. Let it stand for a minute, then wipe up the excess with paper towels. Let the surface dry overnight.
Apply a layer of polyurethane over the wood, brushing it on in a thin, even coat. Let the polyurethane dry for 48 hours before reassembling the cabinet.