Combine the wild rice, water and salt in a saucepan. Bring to a boil, then cover and simmer gently for 40–55 minutes, until the grains are tender and many have split open to show their pale insides.
Drain any remaining water. Spread the rice on a plate or tray to cool for at least 15 minutes.
Whisk the olive oil, lemon juice, mustard, honey, garlic and a good pinch of salt and pepper in a large bowl.
Add the cooled rice to the bowl and toss to coat. Let it sit for 5 minutes so the grains absorb some dressing.
Fold in the pepper, cucumber, red onion, herbs and most of the feta.
Just before serving, gently fold in the avocado. Top with the remaining feta and season to taste.