Preheat the oven to 375 degrees F. Heat a large sauté pan over medium heat. Add the olive oil. When the oil begins to smoke lightly, remove the pan from the heat and add the thyme. The leaves will sizzle and fry a little. Immediately stir in the peanuts, almonds, pecans and red pepper flakes. Mix to coat with the oil.
Spread the nuts on a baking sheet and bake until browned, 5 to 8 minutes. Transfer the mixture to a bowl, stir in the lemon zest and salt and serve immediately?or let cool and then rewarm in a low oven.