4 medium poblano chiles
2 medium red bell peppers
3 medium sweet potatoes, scrubbed, cut
    into 1/2-inch rounds, coated with oil
12 scallions, with green tops intact, trimmed*
4 medium ears corn, husked, silks removed,
    cut into 2-inch rounds
1/2 small pineapple, trimmed and cut into
    1/4-inch rounds
18 corn tortillas
2 Mexican limes, cut into wedges
2 cups fresh tomato salsa

Prepare a charcoal grill, allowing the coals to burn until ash-covered with some red still glowing through.

Place chile and bell peppers in the center of the grill rack directly above the coals and cook for 20 to 25 minutes, turning once or twice, until charred all around. Remove and let cool. Peel and seed all the peppers. Slice into 1/4-inch strips and transfer to a platter. Set aside.

While the peppers char on the grill, arrange sweet potato slices on the rack around the edges of the fire, not directly over the heat. Grill for 15 to 20 minutes, turning once, until golden on both sides and cooked through. Transfer to the platter.

Place onions in the center of the grill with the bulbs facing in and the tops facing out. Place corn pieces between the onions wherever you find room for them, but not directly over the coals. Grill onions and corn, turning once, until the onions are singed, but not burned, and the corn is tender, about 12 to 15 minutes. When done, transfer the onions and corn to the platter with the other vegetables.

When there is room on the grill rack, add pineapple slices, slightly to the edge of the coals - not directly over them. Cook, turning once, 6 to 8 minutes, or until the slices are somewhat soft and nicely charred but still moist. Transfer to the platter.

Place tortillas on the grill and lightly toast on both sides, about 4 minutes altogether.

Arrange all vegetables on a serving platter and pour the collected juices from the kitchen platter over the top. Tuck lime wedges in and around the vegetables. Serve immediately, accompanied by tortillas and salsa on the side.

* Leeks may be substituted for the scallions.