1/3cup good-quality vegetable oil, plus more for brushing
1/4cup minced fresh ginger
Salt and pepper
1 pound tempeh, cut into 16 pieces
8 long or 16 short wooden or metal skewers
1 large red onion, cut into 1-inch pieces
16 cherry tomatoes
1 broccoli crown, cut into large florets (about 8 ounces)
2 tablespoons rice wine vinegar
2 teaspoons Dijon mustard
Instructions
Stir the tamarind, soy sauce, mirin, oil, and ginger together in a small bowl and season with salt and pepper. Reserve 1 cup in a small saucepan, and mix the rest with the tempeh in a shallow dish. Marinate for at least 2 hours, and up to overnight.
Heat the oven to 425°F. If you’re using wooden skewers, submerge them in hot tap water in a rimmed baking sheet for at least 10 minutes. Drain.
Thread a few pieces of onion onto a skewer, then add tomato, broccoli, onion again, and tempeh; repeat on the same stick (or, if using small skewers, start a new one). Repeat with the remaining skewers and put them on a baking sheet; brush them all over with oil, and sprinkle with salt and pepper.
Roast the skewers until the vegetables soften and the tempeh develops a crust, 5 to 10 minutes; turn and roast another 5 to 10 minutes on the second side. Brush the skewers with the sauce and return to the oven for 5 minutes to glaze the tempeh and vegetables; turn and repeat at least once more, until the skewers are golden brown in spots and the vegetables are crisp-tender, another 5 to 10 minutes.
Add the vinegar, mustard, and 1/2 cup water to the saucepan with the reserved tamarind sauce. Bring to a boil and cook, stirring often, until slightly reduced and syrupy. Cool slightly, then taste and adjust the seasoning. Serve the kebabs hot or at room temperature, passing the warm sauce at the table.