In a medium heat-safe bowl, add the tuna and sprinkle with the salt. Add the red pepper flakes, rosemary and thyme.
In a small saucepan or skillet, heat the olive oil and garlic clove over medium heat until hot and fragrant (but not smoking), 4 to 5 minutes.
Pour the olive oil over the tuna and let cool to room temperature, 1½ to 2 hours. Transfer to an airtight container, cover and refrigerate overnight.
Remove the tuna from the oil (discard the oil) and use a fork to break it into loose shards. Add the tuna to a rice salad or pasta salad, or use in a tuna sandwich.