Heat 1 tsp of coconut oil in small frying pan; cook shrimps, sprinkle garlic and onion powder, stirring, until white-orange. Transfer the shrimps to a large bowl.
Slice the avocado in half, discard the seed, scoop it out of its shell and slice it. Slice the tomato, cucumber, and green onions stalk. Add all veggies to the large bowl, cover with lemon juice, and mix well. This will prevent the vegetables from losing their colours. Thinly chop the basil leaves and garlic.
In a small bowl, add the garlic, basil, olive oil, white vinegar, lemon juice and salt and pepper. Mix carefully with a spoon.
Spoon the vinaigrette over the veggies in the large bowl.
Vinaigrette can be made in advance and stored for 2-3 weeks in an air-tight container in the refrigerator. Vinaigrette can be used for a variety of salads. Replace shrimps for chicken for a meat version.