Gujarati Green Soybean Curry

From the garden

• 3 cups shelled edamame, shelled · from about 2 lb of pods; frozen shelled beans work too
• 1 lb waxy potatoes, cut into 3/4-inch cubes
• 1 large yellow onion, finely chopped
• 3 medium ripe tomatoes, chopped
• 4 cloves garlic, minced
• 2 hot green chiles, slit lengthwise
• ½ tsp ground turmeric
• ⅓ cup fresh cilantro, chopped

From the pantry

• 1 tbsp fresh ginger, minced
• 1 tsp brown mustard seeds
• 2 tsp ground cumin
• 1 tsp chili powder · or ground cayenne for a cleaner heat
• 1 tsp sugar · jaggery if you have it; the sweet note is a Gujarati signature
• 3 tbsp neutral oil
• 1 lemon · half squeezed in at the end, half cut into wedges
• 1½ cups long-grain rice · cooked, for serving
• salt · to taste