Spread bread slices in a single layer on a sheet tray. Rub each slice with the cut edge of the garlic. Bake at 350ºF for 10 minutes or until lightly toasted. Crostini may be made ahead and stored in a tightly closed container.
Combine tomatoes, olive oil, lemon zest and juice, salt, sugar, smoked paprika, cayenne and black pepper in a bowl. Mix well. Spoon tomatoes over crostini. Garnish with manchego cheese and serve immediately.