Lovely to see you back on the forum, Dots.
I think you are right that one-pointed attention encourages Natural Samadhi, because doing something like cooking in the way you describe will generate sattva and I am sure that is a pre-requisite. In my own experience the gap more usually occurs when the attention is broadened and relaxed into passive (allocentric) attention, which is normally after the activity has stopped (unless it is something that doesn't require full one-pointed attention). It's then good to try to bring this into the next activity, but unfortunately this is often interrupted by another desire. Others may see it differently and will perhaps contribute their own experiences to this topic?
Although we are told they happen very frequently during the day, I think it might be quite hard to become aware of moments of Natural Samadhi in 'the lowlands' as represented by Stage 1 of the programme in Annex 1 of the paper, as they are so infinitesimally short. (The levels of the mountain referred to above are not official definitions - they were just invented by a member of Cheltenham group - and are open to very different interpretations.) In my experience awareness and extension of them started happening automatically after quite a lot of practice along the lines of Stage 2, when one gets close to the 'middlelands' which is where Stage 3 starts. And when spotted, one can sometimes extend them further. When extended to several minutes, these moments of Natural Samadhi seem to be characterised by calmness, happiness and love of everything and everyone around.
The three basic practices of self-observation, attention and stillness seem to be the key.