Spread the glutinous rice in an oil-free frying pan and set over medium heat.
Cook, stirring often, until browned and nutty in aroma.
Cool the toasted rice before grinding into a powder (use a mini food processor or a mortar and pestle).
Pour the palm oil in a pan and add the annatto seeds.
Heat until the annatto seeds have rendered color.
Scoop out the annatto seeds and discard.
Add the ground toasted rice to the annatto oil and stir quickly to make a roux.
Cook, stirring often, for a few minutes.
Add broth, half a cup at a time and stirring after each addition, until you get the consistency that you prefer (how thick or thin kare-kare sauce should be is a matter of preference).
Place the peanut butter in a bowl and add a few tablespoons of broth. Mix well until smooth.
Pour the peanut butter mixture into the simmering sauce and stir until fully incorporated.
Taste the sauce and add as much fish sauce as needed to get a good flavor balance.