Red Curry Paste

Use a pair of kitchen scissors to cut red chilis (spicy and mild) into ½" chunks, and then slice lengthwise to open up the skin of the chilis. Use a spoon to slide out the seeds. Keep aside whatever amount of seeds you prefer based on your heat tolerance. Discard the rest.
Note: If using dried chilis, then place the skin into a bowl and submerge it with water to soften for at least 30 minutes.
Peel the dry outer layers of the lemongrass and discard them. Roughly cut the bottom of each stalk (about 2 inches) and discard. Finely slice the lemongrass stalks crosswise and set aside.
Zest the limes without going too deep into the white pith (bitter in taste). Squeeze out the fresh juice and set aside.
Toast the coriander and cumin seeds in a dry pan over medium-low heat until they start to pop and release their aromas.
Place all ingredients in a food processor (I used a food processor) or blender. Process several times, and use a spatula to clean the side to make sure it's all mixed well until texture is smooth and pasty. Add a splash of water, if needed.
Note: Alternatively, you can grind it using a mortar and pestle for a coarser texture.
If using a motar and pestle - Pound in order: (1) spices, (2) chilis and lemongrass, (3) remaining ingredients.