Kachumbari is the classic Kenyan salad to accompany dishes, not only meat or fish, but also pilao rice or ugali.
You will find it as an accompaniment to the national dish 'nyama choma' (grilled, almost charred meat) or on the coast to grilled fish (the small, tasty taffi). Local restaurants often pair it with pilao, as mentioned above, and takeaways never lack a little bag (these days a little tray) of kachimbari.
In the "poor" version, only tomatoes and onions appear, seasoned with lemon.
In the richer versions, green peppers, white cabbage and carrots also appear.
The real secret to flavour and digestibility lies in leaving the onion to marinate for at least twenty minutes (or better, an hour) in lime, to make it less "tough" and more fragrant.

Ingredients: 
1 onion
2 tomatoes
A quarter of a white cabbage (Savoy cabbage)
Possibly 1 pepper

Chop up the onions and leave to marinate in lime, cut the pepper, cabbage and tomato into thin slices.
Season with oil, salt and, if desired, lime and fresh chilli pepper.