Prepare barbecue (medium heat). Char poblano and jalapeño chiles until blackened all over. Wrap chiles in paper bag and let stand 15 minutes. Peel, seed, and coarsely chop 2 poblano chiles and jalapeño chile; transfer to processor.
Add feta cheese, sour cream, chopped fresh dill, and lemon juice to processor; puree until smooth. Season with salt and pepper. Cover and chill until firm enough to spread, about 2 hours. Peel, seed, and thinly slice remaining poblano chile. DO AHEAD Can be made 1 day ahead. Keep spread chilled. Cover and chill sliced chile.
Prepare barbecue (medium-high heat).
Brush 1 side of baguette slices with extra-virgin olive oil. Grill oiled side of bread until toasted, about 2 minutes.
Transfer toasts to platter. Spoon about 2 teaspoons chile spread over each toast, top with thinly sliced poblano chile, and serve.
