Cut the cauliflower into florets, and add them to a food processor. Blitz until no large lumps remain.
Heat a dash of oil in a large frying pan or wok, and add the riced cauliflower. Cook over a medium heat for 5-10 minutes, stirring regularly, until the cauliflower rice starts to turn slightly golden brown. Set aside to cool.
While the cauliflower is cooking, add the fresh herbs to the food processor (no need to wash it thoroughly beforehand), and blitz until the herbs are finely chopped.
When the cauliflower rice has cooled, add it to a large mixing bowl, along with the finely chopped herbs, diced cucumber, tomatoes, lemon juice, olive oil, and a good pinch of salt and pepper. Mix thoroughly until well combined. Serve lightly chilled.