I tried to use this code, but it didn't work:
BrewingRecipeRegistry.addRecipe(PotionUtils.addPotionToItemStack(new ItemStack(Items.POTION), PotionTypes.AWKWARD), Ingredient.fromItems(ModItems.PEARL), PotionUtils.addPotionToItemStack(new ItemStack(Items.POTION), ModPotions.POTION_TOUGHNESS));