1Chutney: Combine peanuts, cucumber, coconut, lime juice, sugar, and salt. In a small saucepan, toast mustard seeds for 1 minute, then add oil and chile for one more minute over medium heat. Cool and combine into chutney.
2Watermelon: Brush the watermelon sides with olive oil, and grill on high heat. Sear, but do not cook! Once you have searmarks, you are done. Remove from grill.
3Top chutney on watermelon and serve immediately.