In a food processor, combine the lemongrass, shallots, garlic, brown sugar, coriander, cumin, turmeric, fish sauce, salt and the 2 tablespoons of canola oil and process to a paste. Transfer the marinade to a bowl and add the chicken, gently tossing to coat each piece. Thread the coated chicken pieces onto 12-inch skewers and refrigerate for 30 minutes and up to 1 hour.
In a medium saucepan, heat the canola oil. Add the shallots, garlic, lemongrass, jalapeño and ginger and cook over moderate heat, stirring, until the aromatics are softened and browned, about 10 minutes. Scrape the mixture into a food processor. Add all of the remaining ingredients along with 1/2 cup of water and process until a smooth paste forms.
Scrape the peanut paste back into the saucepan and cook over low heat, stirring frequently, until very thick and the fat separates, about 20 minutes. The peanut sauce will turn a deeper shade of brown. Whisk in 1/2 cup of hot water until incorporated. Keep the peanut sauce warm over very low heat.
Light a grill and oil the grates. Grill the chicken skewers over moderately high heat, turning occasionally, until charred in spots and cooked through, 10 to 12 minutes. Serve with the peanut sauce.