I've had call to make spice pastes by using a food processor. Rather than using the full-sized bowl, which is way too big, my food processor has a milling attachment designed for coffee beans. However, whenever I try making spice pastes in this, it only gets so smooth before becoming clumpy and the blades effectively spinning at nothing. (Ginger and coconut are particularly bad at not reducing down further than grit.)
Adding more water usually helps to make a finer paste, as it forces everything together somewhat and causes the mixture to act more as a liquid than a powder. However, that makes the paste too wet (it's a paste, not a sauce, after all!)
Is a food processor/mill not the right tool for the job, or am I just doing it wrong?