Cook up the onions in the oil if you're not using leftovers like me. About 10-20 minutes, until softened and golden. Remove from the pan.
If you're just starting with leftover onions, heat a bit of oil in the skillet over high heat, then add the mustard and cumin seeds. Cover and cook about 30 seconds, shaking the pan. You'll hear them start popping. Remove from the heat until they stop popping.
Add the peas and onion back to the pot and cook until hot. Add salt and pepper to taste and serve.
Spiced Peas and Onions from Sarah Moulton https://cheapcooking.com/spiced-peas-and-onions-from-sara-moulton/ December 4, 2010