Whisk the lime juice and the sugar together in a small bowl.
Add the onion to the lime juice and sugar and massage the liquid into the slices with your fingers. Set aside.
Sprinkle a little salt over the halved cherry tomatoes. Set aside.
Place the brown rice, chopped salmon, cucumber together in a bowl.
Sppon the avocado over the top with a teaspoon.
Add the cherry tomatoes and the red onion, drained of its liquid. Reserve the liquid for the dressing.
Whisk together the lime and sugar mixture with the sesame oil. Taste for seasonong. Add freshly ground pepper, and add a little more salt if you think it needs it.
Pour the dressing over the top and mix everything together gently.
Sprinkle the mint leaves over the top and serve with lime wedges on the side.