In a small frying pan put 1 Tablespoon oil, 1 teaspoon black mustard seeds, and 1/2 teaspoon cumin seeds. Heat over high heat until the mustard seeds have popped for about 5 seconds. Remove from heat and set the mixture aside to cool.
In a glass casserole dish or serving bowl put 3 peeled and pitted large avocadoes. Add 1 Tablespoon lemon juice and 1 minced garlic clove, Mash well with a fork.
Stir in 1 minced Serrano chili and salt to taste.
Add the mustard and cumin seeds that were fried in oil and mix again.
Chill in the fridge until serving time. Serve with pappadums or tortilla chips.
Variations: Exchange the cumin seeds for ground cumin and add the cumin powder with the salt. Other items that can be added are: one small deseeded and finely chopped tomato, 1 Tablespoon beaten yogurt, and/or 1 Tablespoon minced cilantro (added with the salt).