My preliminary plan is to install LED undercabinet lighting and recessed par20 downlights. One row of downlights would be located between the upper cabinet and the edge of the countertop, and spaced about 3-ft apart. A parallel row would be spaced about 42-in. away, in the open area of the kitchen.

One concern is about all the reflection in the ubatuba countertops. I am wondering if instead of downlights over the work surface, it might make sense to use wall washers aimed at the upper cabinets. Another concern is whether either plan will adequately light this kitchen, which basically has no natural light source.

Any comments or suggestions gratefully accepted!

Wall washers may not provide sufficient task lighting since they are usually used for decorative purposes.

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The rule I used was to achieve ~ 35 lumens per sq ft.
Take the light output from the individual components that will make up the main lighting. eg - 1 recessed can. Assume ~ 600 lumens per can
Calculate the total sq footage of the kitchen * 35 and divide that by the output per can.

Adjust as necessary - lower lumens per sq ft?
Higher luminous output for individual cans?

Note that the formula I used grossly simplifies things.
For instance
1. It assumes that the light sources are not directed spotlights.
2. The distance from the light source is not taken into consideration.
3. The spread of the light beam is not considered as the actual placement of each light source is subject to other considerations.