Place a large frying pan over low heat.
Add coriander seeds, cumin seeds, cloves, black peppercorns, poppy seeds, mustard seeds, fenugreek seeds, nutmeg, red chilies, bay leaves, cardamom pods, cinnamon stick and mace (if using) in a pan over low heat.
Stir continuously for about 5 minutes or until the spices are roasted and aromatic.
Add ground turmeric. Stir again for a few seconds.
Remove from heat.
Place in a spice grinder or small food processor. Grind to a fine powder.
Store in an airtight container at room temperature for 3-4 months.
The aroma and freshness of the spice mix may decline gradually overtime, so make it in small quantities for maximum flavor.