To make dressing: In a mini-food processor or blender, add scallions, 1 tsp jalapeno pepper, cliantro, lime juice, and salt; pulse to combine. Taste and adjust flavour as necessary.
To make salad: Arrange lettuce leaves in bottom of a large serving dish. Add tomatoes, then clinatro leaves, crumble ricotta over the top and sprinkle with scallions. Place avocado in centre. Serve with dressing on the side.