Special equipment: toothpicks
For the salsa brava: Heat the oil in a medium saucepan over medium heat. Add the onions and saute, stirring occasionally, until softened, 5 to 7 minutes. Add the garlic and saute until fragrant, about 2 minutes more. Stir in the piment d'espelette and fry for another minute. Add the sugar, vinegar, canned tomatoes and 1/2 teaspoon salt. Reduce the heat to low and simmer, stirring occasionally, until the tomatoes have broken down and the flavors have had a chance to meld, about 10 minutes.
Remove from the heat and stir in 1/4 cup water. Carefully puree the mixture until completely smooth, using an immersion blender or in batches in a blender. If the sauce is too thick, add water 1 tablespoon at a time. Taste and adjust the seasoning. (Makes about 2 cups.)
For the ham and cheese bites: Cut the baguette on the diagonal into 1/2-inch slices. Slather each slice with some salsa brava and top with a piece of ham, a slice of cheese and an olive. Insert a toothpick to hold everything in place.