If you see lumps in your curd, it’s most likely overcooked egg bits. Your temperature was too high while cooking curd. Remember low and slow is the key to silky smooth creamy curd. You shouldn’t see any bubbles while cooking curd. If you are having trouble with temperature, it's the stove. Best use a double boiler to make silky smooth curd (cooking in a double boiler will take a slightly longer time for the curd to cook). Don’t worry if there are lumps in the curd. Pass the curd through a fine-mesh strainer and strain bits and lumps from the curd; you’ll get silky smooth curd. If curd breaks and is too lumpy or curdled to pass through a strainer, blend the curd in your blender until smooth.