Prepare the lemon vinaigrette by combining lemon juice, minced garlic, minced shallots, salt, and pepper in a medium bowl.

Whisk the ingredients together until well combined.

Gradually add olive oil in a steady stream while whisking continuously to emulsify the vinaigrette.

Adjust the seasoning with additional salt and pepper to taste.

Prepare the couscous salad by placing couscous in a large bowl.

In a saucepot, combine water, harissa, minced Italian parsley, minced cilantro, salt, and pepper.

Bring the mixture to a boil.

Pour the spiced, boiling water over the couscous and cover the bowl with saran wrap or a lid.

Let the couscous sit for 20 minutes to absorb the liquid.

Use two forks to fluff the couscous.

In a large bowl, combine crab meat, sumac, diced sweet peppers, serrano chili, and the prepared couscous.

Add 1/2 cup of the lemon vinaigrette to the couscous mixture.

Season the salad with salt and pepper to taste and toss to combine.

In a separate large bowl, toss watercress and julienned tomato with the remaining 1/2 cup of lemon vinaigrette.

Season the watercress and tomato salad with salt and pepper to taste.

To serve, place 1/2 cup of couscous salad in the center of four salad plates.

Top each couscous portion with 1/4 of the watercress and tomato salad mixture.

Serve the salad immediately.