Heat 1 teaspoon oil in a saucepan. Once hot, add the chayote squash skin and cook for 20-30 minutes. Remove and let it cool.
Heat a clean saucepan with 1 teaspoon oil and roast the dry red chilies followed by urad dhal and finally tamarind pulp. Saute for couple of minute. Switch off the flame and add the coconut. Let the remaining heat cook the coconuts. Remove and let it cool.
Grind together the cooked chayote squash, roasted urad dhal, dry red chilies, tamarind and coconut with minimum water to a smooth paste . Add salt to taste. Mix well.
Heat 1 tablespoon oil in a small pan. Once hot, add mustard seeds and let it pop. Then add the curry leaves and asafoetida. Pour this mixture over the chayote squash / chow-chow thogayal. A South Indian pesto with chayote squash to ready to devour.