Combine the malagueta peppers and salt in a mortar and pestle, blender, or food processor and process until a thick paste forms.

Gradually add the onion and garlic, processing and scraping down the sides as needed until incorporated into the paste.

Add the lemon juice and process again.

Transfer the sauce to a glass bowl, cover, and let stand for 30 minutes.

Heat the olive oil in a large skillet over medium heat.

Add the chayote and sauté, stirring occasionally, for about 10 minutes, or until fork-tender.

Add the salt and pepper, remove from heat, and let cool.

Chill in the refrigerator for 2 hours.

Arrange the chayote slices on a platter and drizzle with the sauce.