Tomato and Onion Salad

1 cup sliced red onions
4 ripe medium tomatoes, sliced
½ cup chopped parsley
¼ cup olive oil
2 tsp lemon juice
2 tsp wine vinegar
1 tsp chopped basil
½ tsp sugar
Salt and ground pepper to taste

Arrange alternate slices of onions and tomatoes on a chilled serving dish and sprinkle with remaining ingredients, which have been mixed well.