Put the cumin seeds in a 9-inch skillet and dry-roast over medium-high heat, sliding the skillet back and forth to ensure even roasting until the seeds are fragrant, about 45 seconds. Remove to a plate to cool.
Add the coriander seeds and Thai peppercorns to the skillet and dry-roast for about a minute or less, until they exude a pleasing aroma.
Transfer to the plate with the roasted cumin seeds.
Cool the seeds, before they grind in an electric spice or coffee grinder.
Transfer the ground spices to a large shallow pan and add the palm sugar and soy.
Add the beef, stir well to coat thoroughly, cover, and marinate overnight in the refrigerator.
Put the marinated steak on wire cooling racks and dry in the sun for a day, turning occasionally to ensure even drying.
Alternatively, dry the marinated steak in a 150 degree F oven for at least 8 hours, until they are dry and leathery.
Store in the refrigerator.
To serve, shred and deep-fry in hot oil until crispy.