Cook beans in boiling, salted water to cover on high heat, for 4 minutes, until tender but still with a bite. Drain and refresh with cold water. Drain again.
Make dressing by combining all ingredients in a bowl. Season to taste and add green, kidney and cannelloni beans. Toss to coat. Arrange sliced tomato on a dish. Top with beans and sardines. Garnish with extra small basil leaves.